But these days, the fans who stuck with him are getting their patience rewarded by a new, improved Rick Shapiro.

A recent Thursday evening was typical of Mr. Shapiro’s vastly upgraded juju. He brought down the house with his one-hour comedy set at the Sidewalk Cafe in the East Village. His end-of-set riffing was going so well, he finished 15 minutes over his allotted time.

"Do you ever feel like a loser when you’re cleaning up your apartment?" he asked the crowd at one point. "You’re just pouring Lestoil and you’re like, ‘Wow, man, I’m a loser—this is taking care of shit.’ And you’re too lazy to use water, so you mop it over and then for two days your throat closes and you wonder why you can’t eat? And you’re waking up with headaches and you’re like, ‘Oh, I got a buzz! This is good!’"

The audience hung on his every word.

Outside after the show, Mr. Shapiro smoked a cigarette and paced on a small patch of sidewalk. He hunched forward, holding his elbows tight to his sides; it was freezing cold outside, but he wore a jean jacket wide open at his bare chest, a thick, black leather belt wrapped around his wiry midsection, not quite holding up his skin-tight bell-bottom jeans. He kept reaching into his pocket, checking on a thick wad of cash tips.

A sprightly, short-haired young woman marched up to him. Her name was Marie, and she was a Russian immigrant from Greenpoint, with John Lennon spectacles and a ring beneath her lower lip. She was, she said, a Rick Shapiro fan.

Mr. Shapiro blurted out a response. "You think I’m thinking, ‘Oh, she likes my show—let’s fuck.’"

"Oh, no no nooooo," she said, laughing, waving her hands in front of her face.

"I mean, that’s not what I’m ridin’ on, but it’s in the back of there someplace," Mr. Shapiro said.

By the end of their exchange, he’d managed to get Marie’s phone number.

"So, do you think she’ll go out with me?" he asked me. "How long am I supposed to wait to call her?"

It was hardly an award-winning pickup attempt, but still—he was passable as the kind of straight, regular person who goes on dates with women he meets after work. The whole evening represented progress.

The 44-year-old Mr. Shapiro has plowed through a half-dozen managers and spent months in psych wards and rehab programs. Each new manager has thought that he’d be the one to take Mr. Shapiro to the top, only to watch the comedian crash and burn. The pattern would seem to be continuing: This March, his latest manager temporarily left the business, and Mr. Shapiro is now on his own, performing at the same kind of downtown and off-Broadway clubs where promoters tapped him for stardom more than a decade ago. Yet again, he is being courted by several agents and managers who long to be the next Rick Shapiro evangelist.

This time, though, everyone around him agrees that something is different. With the help of his umpteenth therapist, it looks like Mr. Shapiro finally has himself under control. His steady five-nights-a-week gig at the Village Lantern is a long way from the period a few years ago when he scraped by on welfare, surviving on pierogies from the Ukrainian diner Odessa. Mr. Shapiro has even been appearing regularly on Comedy Central shows like the comic roundtable Tough Crowd with Colin Quinn. It’s all enough to make you believe the word in the comedy world about Mr. Shapiro: Success this time is his to lose—and he’s sick to death of losing.

"His whole approach to things has changed dramatically," said Jason Solomon, one of a long list of former Shapiro managers. "He’s a lot more professional." Gone are the days of showing up late to a gig (or not showing up at all), and his signature hour-long rants are being reshaped and reined in to pack an acute punch.

"It’s like starting over again. It’s scary to be there," Mr. Shapiro said over lunch at an uptown Chinese-Mexican restaurant a few weeks later. Now, he said, "it’s going to move forward. It’s not going to be me destroying myself."

Mr. Shapiro returned to the Sidewalk cafe the following Thursday, midway through a 12-week run of shows that ended last week. He performed, as always, in the Fort, a small, T-shaped room in the back, where old instruments, chalk drawings of Dixieland bands and rectangles of reddish lights covered the walls.

Onstage, Mr. Shapiro morphed seamlessly from old Irish bartender to horny gay man to flirtatious female art student. With both hands, he fretfully brushed back his black-with-a-tinge-of-silver hair from his receding hairline, sometimes gripping his scalp with his fingers.

He often yelled and spit into the microphone ("A lotta white comics say ‘penis.’ It’s COCK!") during a frenzied, attention-deficit whirlwind of a routine. He spewed venom at the audience, at run-of-the-mill "observational" comics and at accepted social niceties.

"I have to get AIDS," he said midway through the hour-plus performance. "Because that’s the only thing that’ll put me in a good mood." The crowd seemed unsure whether to feel sorry for him or laugh. "I can’t think positively unless I have AIDS. Because then it’s the bottom line. You have to think positively when you have AIDS—you got nothing left! You’re like, ‘Oh my God, my skin’s peelin’ off, my lover’s leaving me, I didn’t know I was gay!’"

Most of the audience laughed. Two gay men stood up and left the room.

Carol Burnett once called comedy "tragedy plus time." Mr. Shapiro has dispensed with the time lag: For him, comedy is tragedy, period. When he told a joke about 9/11, or about suicide, or about priests nibbling on little boys’ testicles, his words moved so fast that most of the audience had laughed before they’d even realized that they should be disgusted or depressed.

"Girls are funny, right?" Mr. Shapiro asked himself. "Girls are fucked up, man. It’s like I have to wear a shirt or you won’t go out with me. I just wanna do coke, and I’m off it 17 years. You know what I realized? Eight-year-old girls are the only ones left I can have relationships with. They’re the only ones who don’t try to change me. They love Uncle Ricky for who he is."

Then came the half-cracked non sequitur transition to the next bit: "And torsos are my only pleasure, because they appreciate every move in bed. They have no arms and no legs and they go: ‘Do it again, man—I’m just glad you’re here.’

"‘What are you, desperate?’" (Mr. Shapiro intervening in his own bit as a third-party interlocutor.)

"‘Who, me?’

"‘No—the torso!’

"You ever fuck a head that had a thumb sticking out of its neck but it’s alive, it just had no body?" Mr. Shapiro concluded. "Oh, you gotta go to Venice Beach!"

With its almost poignant undercurrent, the Shapiro shock factor ("Have you ever freebase-fucked a homeless woman?") exists several notches above your average raunchy club comedian. He’s as much a performance artist as comic: At the Sidewalk that night, Mr. Shapiro began to spin a tale of a cabdriver who asked him to have anal sex with bunny rabbits.

"Let’s just say that rabbit’s ass was made of sulfur and a giant flame of blowtorch," he said as the taxi-driver character. "And broken glass, rusty knives, swords that were not used in Masterand Commander."

Mr. Shapiro started to yell, as Elvis Presley’s "Suspicious Minds" played loudly over the P.A. system: "And the teeth of your grandmother after she chewed on pus, sharks’ teeth—not the kind that yoga people eat—glass and disease flying around and guns firing and saws being pulled back and forth by carpenters who gave up on their dreams."

And then he stopped.

"And that lit-tle baby’s face," Mr. Shapiro whispered into the mike. "Its smile was being held up by seven Asian children, with bangs held up by red balloons."

"I go by William Blake," Mr. Shapiro said later. His extreme humor, he continued, is a form of searching for truth. "‘The potential for prophecy lies deep within everyone.’ You think you ain’t getting it? You’re getting it—even if you’re walking out. I’ve seen the way people walk out. They don’t walk out like they’re not getting it."

At 3 a.m. the next Tuesday, Mr. Shapiro slid into the booth of the Westway Diner in Hell’s Kitchen, where Jerry Seinfeld and Larry David purportedly hatched the original plans for Seinfeld. He had just finished a set at Ha! Comedy Club, where he was working on boiling down an hour’s worth of jokes into the seven-minute routine of a normal comic, which he would need for at least some shows if he ever planned to work the national club circuit.

The city’s hundreds of diners and coffee shops are Mr. Shapiro’s main sources of solace, the places where he can write and try out new material in peace. For someone like Mr. Shapiro, who normally heads to bed around dawn, they’re also a great way to avoid going home to his tiny sublet apartment on West 65th Street. He eats almost every meal at diners, and claims he once walked from the Village up to 76th Street and waved to at least one waiter in every coffee shop on the way. It’s hard to believe, until you follow Mr. Shapiro into several coffee shops around the city and hear "Heyyyyy, Ricky!" from the owner, the waiters and the immigrant busboys.

Mr. Shapiro yawned and slumped down, critiquing and cursing that night’s mediocre set and the other performers. I tried to get him to give me a quick autobiography, but over the next two hours, every question led to a tangent, which would then branch off to another story, with two or three nested tales in between.

"We jump around and I get confused," he complained, chewing away at his Buffalo wings with tiny bites, like a chipmunk.

What can be gleaned is that Mr. Shapiro had a deceptively normal suburban childhood in Oakhurst, N.J., near Asbury Park. His father was the dermatologist for the New York Knicks, his mother a social worker. He earned D’s and F’s in most subjects, but scored A’s in English. By 12, he was writing poetry and plays, which his "practical" father tore up.

Mr. Shapiro started college nearby, but fled to New York University, where he dated girls from Manhattan prep schools, washed dishes and gambled to make enough money to afford to take them out. He was soon mired in debt. To pay it off, the shy, cute kid from New Jersey became a prostitute. He worked the clubs on East 54th Street, and wealthy middle-aged men took him home to opulent apartments. The coke habit and heroin addictions Mr. Shapiro soon picked up drove him further into the vortex of hustling.

"I can’t believe what I let myself do," he said, cringing.

It took him seven years to escape, but those experiences have provided some of the best fodder for his comedy. He sells bumper stickers that say: "Rick Shapiro: I Sucked Dick for Heroin."

In a quiet moment in another coffee shop, probably around 1987—he’s not sure exactly when—Mr. Shapiro decided to get clean. He became more serious about acting and standup, something he’d done on and off since college. During a long New York tenure punctuated by two short stints in L.A., he was crowned the next big thing over and over again by the critics and his peers. He had a recurring character, "the Angry Poet," on Late Night with Conan O’Brien and starred in Late Night writer Louis C.K.’s cult short films. Comedian Dave Attell once called him up, asking, "How does it feel to be the new genius in town?" Yet, as many of his friends became stars on shows from Saturday Night Live to The Sopranos, Mr. Shapiro never broke out.

Each time he came close, he told me, he self-destructed. Mr. Shapiro was thrown off Late Night because, on an Earth Day segment, he went off-script, drop-kicking a globe, which prompted the audience to break out chanting, "We ain’t doormats!" He lost a small role in a Damon Wayans movie when he yelled "Fuck you!" at a production assistant and threw lasagna at him during lunch break in Washington Square Park. The WB called him in for a pitch meeting, and he was so cocky ("We think you’re hysterical!" "Yeah, I know") that they didn’t invite him back.

One night, about 10 years ago, Mr. Shapiro hit bottom. He closed the blinds of every window in his Los Angeles apartment and refused to leave. His nerves were going wild. He got into bed and pulled the sheets up to his nose and just lay there, shaking.

His manager at the time, Jason Solomon—Denis Leary’s manager—had brought him from New York to L.A. just months before. For 13 straight weeks, Mr. Shapiro had packed the theater above the famed Improv comedy club. He was on the short list for a movie lead opposite Eddie Murphy. The producers of Seinfeld wanted him for a role that might have become a regular character. After nearly 10 years as an actor-comic with great "potential," Rick Shapiro was finally about to make it.

Instead, he panicked. "I couldn’t handle the nerves anymore," Mr. Shapiro said.

He checked himself into the psychiatric ward at Cedars-Sinai, where he remained for two weeks. On the day of the Eddie Murphy callback, he was on a plane, flying home to New York.

"He kind of self-sabotaged," Mr. Solomon said.

Self-sabotaging, it seems, was what Mr. Shapiro did even better than comedy.

"I think Rick is a comic genius—probably the most important comic of our time," said Lach, the mononymous owner of the indie label Fortified Records and a fixture of the downtown Manhattan entertainment scene—and also an ex-Shapiro manager.

While most of Mr. Shapiro’s friends and managers said it’s this self-destructive nature that has held him back, others believe it’s just the nature of his act. Much of his material just doesn’t translate to television, where most young comics first gain national exposure.

"On television, he can’t say half the things he does onstage," said Jeff Singer, a producer at Tough Crowd, who said he hopes that Mr. Shapiro will someday get a chance to perform on a network like HBO, where he wouldn’t be as constrained.

"His stuff is outside the realm of commercial TV," Lach agreed.

Mr. Shapiro’s latest almost-hit-the-big-time saga wasn’t the result of his own doing—it was just pure showbiz bad luck. In late February, he was set to star in a highly anticipated Off Broadway show: a word-for-word reproduction of Lenny Bruce’s legendary Carnegie Hall performance of Feb. 4, 1961. The word was that Lenny, created by original Carnegie show’s producer, Don Friedman, would propel Mr. Shapiro to fame and fortune. Then, with little warning, some of the show’s backers pulled their funding, and Mr. Friedman was left with a star, a script and no money to put on the show. A few weeks later, because of personal problems unrelated to Mr. Shapiro, his manager quit the business and left New York. The status of Lenny now remains in limbo, and Mr. Shapiro is plugging away at clubs like the Village Lantern and Stand-Up New York, turning down offers from new managers and waiting for the right one to come along, hoping that if he chooses wisely, the decision might lead, finally, to his big break.

Mr. Shapiro was so nervous, walking onto the set at his second appearance on Tough Crowd the next Thursday afternoon, that he stepped past the spot where he was supposed to sit. His hair was neatly brushed, and he almost would have looked presentable if not for the rip across the knees of his jeans. Mr. Shapiro sat with his elbow resting on the back of the chair, like he was "about to get up and leave," supervising producer Ken Ober told him after the show.

On Tough Crowd, Mr. Quinn and four comics argue and joke about current events, and during the taping, Mr. Shapiro competed with comics a decade younger than him for airtime. Many of their jokes bombed—the producers edit out the least-funny material before broadcast—but most of Mr. Shapiro’s one-liners got big laughs from the studio audience. During a discussion of sex workers near the Mexican border, the roaring laughter from the crowd when Mr. Shapiro said, "Well, if you’re a consumer of handjobs, I believe that—" nearly drowned out the rest of his commentary.

"Rick’s killin’ ‘em," Mr. Quinn said to the audience near the end of the show.

Mr. Shapiro’s jokes were slightly tamer than his standup act, but they were also shorter and snappier. On every issue, Mr. Quinn motioned toward Mr. Shapiro, giving him the chance to weigh in. He was clearly the evening’s alpha comic.

"I don’t think I’ll ever be that normal comic," Mr. Shapiro said in yet another diner after the show. "There’s all different types of comics. In a way, I’m carrying a sword, I’m cutting through a bunch of bullshit—whether I make it or not. I hate people saying how brave we are because we’re comics. In this business, you’re afraid all the time," he said. "I think I’m gonna make it. I gotta not worry so much, I guess."

Mr. Shapiro chuckled to himself and took a sip of his coffee, his hand shaking slightly. Then he rushed into a cab. He had another show to do at the Sidewalk, and if he didn’t hurry, he might be late.