The mellowing of Clint Eastwood continued to astound me.This bewildering evolution began in a tentative way in th last half of "The Gauntlet." It was pursued throughout "Every Which Way But Loose," a ramshackle success that indicated Eastwood's fans were prepared to accept him as a vaguely likable chump in a brand of knockabout farce obviously influenced by the big Burt Reynolds hits but executed with no discernible expertise.

"Bronco Billy," the new Eastwood vehicle, is a cockamamie elaboration of the contradictory motifs and crowd-pleasing aspirations that cluttered up "Loose." Determined to be all things to all audiences -- paragon and stooge, reactionary and liberal, lunatic and lover, good guy and bad hombre -- Eastwood is stradding so many genres and constituencies that it's rather like Harold Lloyd trying to mount a trolley car while burdened with dozens of bundles and a live turkey.

Formally speaking, "Bronco Billy" is a turkey. A chronicle of the would-be wacky, endearing travels of a small-time Wild West Show in the contemporary West, the movie's scenario really deserves to be preserved under a bell jar in some sideshow devoted to the freakiest plots ever committed to celluloid. I don't know if Eastwood loyalists will be fazed by this undigested collectionon of screwball, romantic antagonism, dangling subplots, flimsy explanations and obtrusive heartfelt orations, but it defies coherent synopsis.

The major plot thread is easy to recognize, if unrewarding to follow. As Bronco Billy McCoy, a somewhat foolish but fundamentally lovable nostalgic dreamer and showman -- the founder, star and impresario of a tenacious little band of dreamers -- Eastwood is meant to find an unlikely romantic match in Sondra Locke's Antoinette Lily, a snooty heiress abandoned in Idaho by her bridegroom, Geoffrey Lewis, and forced to seek refuge with the Wild West troupe. Under their humanizing influence, she is destined to change her arrogant ways and behave like real folks.

Fair enough, but the movie is so shabbily written (by Dennis Hackin) and unevenly directed (by Eastwood himself) that the traditional obstacles to romantic comedy consummation are overwhelmed by superfluous complications and imprecise calculations. Locke's supercilious act leaps to mind as one element that needs finer directorial tuning. Allowed to be as frosty as Cybill Shepherd at her most disagreeable, Locke is ill-prepared for the eventual thawing out.

Eastwood's comedy timing is so precarious that one isn't always certain which jokes were intentional and which inadvertent. It's obviously intentional when Bronco Billy is shown being solicitous about the children he refers to as "little pardners" and offers advice like, "I think every kid in America oughta go to school -- at least up to the eight grade" or improvises a prayer that begins, "Show them the way to a good life so they don't get tangled up with hard liquor and cigarettes."

On the other hand, it can be funnier when he gets tangled up in lines that are just badly written: "She couldn't cut the bacon. I'm glad she got out of the fryin' pan before I wasted time on her." When Antoinette expresses her exasperation at Bronco Billy to the only other woman in the company, Lorraine Running Water (played by Sierra Pechear), she is told that "The Apaches had a word" for such vexation -- they called it "love." And she is subjected to an impromptu analysis of devastating banality: "Don't you realize what the Wild West Show is all about? You can be whoever you want . . . I don't know where you came from, but I do know you're running away from yourself. Until you decide who you're gonna be, you'll never find yourself."

The Wild West Show itself possesses certain basic credibility problems. Since it appears that ringmaster Scatman Crothers has only three acts to introduce every time the show goes on -- Eastman's trick riding and shooting, Sam Bottoms' rope twirling and Dan Vadis' rattlesnake dance -- it's difficult to see how the troupe could entertain even scattered customers for more than about 30 minutes. Maybe Bronco Billy does reading from Robert W. Service after the interval.

Although the plot weaves all over the landscape, stopping dead for episodes in which Bottoms is revealed to be a deserter and Lewis a preposterous fall guy and Locke is suspected of being a jinx, Eastman may get away with the sloppiness by simply tacking on a happy ending. Despite the circuitous trip, audiences may be satisfied with the assurance that all's well that ends well.