When you think of Clint Eastwood, one of the first words that comes to mind is lean. It describes the man himself: the tall, erect physique and the stretched-leather gauntness of his features. And it describes the flinty reticence of his moviemaking style-the way all his characters are emotionally stripped down for action. I’m afraid, though, that lean is not a word likely to occur to many people in connection with A PERFECT WORLD (PG-13), the first film Eastwood has directed since Unforgiven. Like his dark, Oscar-winning Western, this movie is set in a mythic American past-we’re in Texas in November 1963, the moment just before the country’s psyche was blown open by the JFK assassination-and it’s structured as a leisurely, epic manhunt. The man being chased is Butch Haynes (Kevin Costner), a lifelong criminal who breaks out of Huntsville Prison, where he was serving a 40-year sentence for armed robbery. He takes a hostage, 8-year-old Phillip Perry (T.J. Lowther), and the case becomes the hottest news in the state. Before long, the two are under pursuit by Red Garnett (Eastwood), a veteran Texas Ranger who, along with his crew of deputies and a feisty federal criminologist (Laura Dern), is traveling in a silver trailer that has been equipped for use as a mobile command center. For virtually its entire 2-hour-and-18-minute running time, A Perfect World cuts back and forth between Butch and Phillip as they make their way past one sunbaked cornfield after another and Red and his team as they drive past the same cornfields. Nothing much happens. Butch may be a hardened convict, but he’s a super-nice guy. Occasionally, he and Phillip stop off at a diner or a small-town store, where every waitress and clerk seems to throw herself at Butch. Butch never seems to be in any danger, though: Everyone is too scared- or too slow-to report him. Meanwhile, even less is going on within that silver trailer. Eastwood and Dern exchange a few testy barbs, just as Eastwood has always done with his female law-enforcer comrades-before learning to respect them, of course. In essence, though, we’re watching a bunch of detectives while away the hours before confronting their prey. The way A Perfect World sets cop and criminal on parallel tracks would seem to make it the third entry (after The Fugitive and In the Line of Fire) in this year’s sturdiest thriller genre. The difference is that this one is stately, becalmed-and surprisingly dull. It may be the single most bloated movie Eastwood has ever made. Unforgiven didn’t have that much more story line than this movie does, but there Eastwood gave us characters who were knee-deep in moral squalor. Now the director’s brooding terrain has been invaded by sweetness and light. The core of A Perfect World is the bond that develops between Butch and his young hostage. Phillip, you see, has grown up emotionally deprived. His father abandoned the family, and since Phillip is a Jehovah’s Witness, he has never been allowed to do normal kid stuff like going out for Halloween. Butch can identify: His own father was a criminal lout. Overnight, Butch becomes the father Phillip never had. As the two head for Alaska, he talks warmly to the boy, takes him trick-or-treating, even reassures him that the size of his penis is A-OK. Speaking in a honey-smooth drawl, Costner is warm and appealing. In fact, he’s too appealing: He’s so much in his straight-arrow, New Age Gary Cooper mode that, despite the fact that Butch is capable of killing without hesitation, A Perfect World loses almost any pretense of being about a pathological crook. Costner seems about as pathological as a koala bear, and his gentle charisma reinforces the film’s touchy-feely theme: that the real criminal in American life is the Absent Dad. As Phillip, T.J. Lowther doesn’t have much to do but stare admiringly at Costner and behave like a shy chipmunk. A Perfect World becomes a loopy cross between Badlands and Field of Dreams. Beneath its road-movie surface, the film has a daytime-talk-show squishiness-it’s Eastwood’s version of ”Violent Criminals and the Fathers Who Didn’t Love Them.” Near the end, Costner finally gets an interesting scene. Holed up in the home of a black family, Butch explodes at the grandfather (who keeps whacking his grandson), and his obsession acquires a psychotic edge. Moments later, though, the film snaps back to viewing him as a dust-bowl saint. The trouble with Eastwood’s attempt to make a thriller with ”heart” is that, in retreating from his darker impulses, he muffles his own voice as a moviemaker. Of all directors, he should know that a character like Butch can’t be this easily forgiven.