Too lightweight for its own good, "Foolin' Around" probably began with the amiable desire to make an old-fashioned romantic comedy in an acceptably modern setting. "Hero at Large" succeeded in turning this anachronistic trick earlier in the year, although the movie seemed to end just in the nick of time, sparing the filmmakers from pressing their luck and plunging into mawkishness.

"Foolin' Around," now at area theaters, never gets coordinated enough to risk a collapse. It's all trivial, ineffectual flutters of amusement, with nothing sustained or accomplished. The most regrettable aspect of this weightless, vaporous quality is the waste of considerable acting talent: Gary Busey, Annette O'Toole, Cloris Leachman, Tony Randall and Eddie Albert, to mention only the familiar personalities.

It's possible that the screenplay, credited to Michael and David Swift, was once intended for the Disney organization, where Swift used to write and direct juvenile hits like "Pollyanna" and "The Parent Trap." The plot is designed to unite Busey, a hard-working, easygoing country boy from Oklahoma, with O'Toole, the attractive coed heiress to a construction company founded by her maternal grandpa, Albert, and run by her ambitious, oft-divorced mother, Leachman.

The stumbling block to true romance is mom, who prefers that her daughter marry a social-climbing stuffed shirt played by a young actor with the formidable name of John Calvin. Ironically, he turns out to be an amusing ringer for Sonny Tufts, the meteroric matinee idol of World War II.

The setting is a Midwestern college metropolis, represented by Mineapolis-St. Paul, where the hero is belatedly beginning a college career and the heroine appears to be a graduate assistant in psychology. Indeed, they Meet Cute (far too cute, I'm afraid) when he volunteers for a Pavlovian experiment that she happens to be conducting, or rather misconducting, for predictable farcical yuks.

The comic authenticity and sensitivity of "Breaking Away" may place "Foolin' Around" at a particular disadvantage. I found myself becoming impatient with this perfectly harmless movie. On one hand it can't compare with "Breaking Away." On the other it runs an equally distant second to "National Lampoon's Animal House." As either collegiate romantic comedy or collegiate farce, it remains stubbornly underwhelming.

Although Busey and O'Toole suggest appealing, unconventional romantic possibilities, they're also too grown-up for the level of fooling around this script is content to exploit. For example, the hero's gaucheries and farcical stunts would be more appropriate in a movie starring the Kurt Russell or Bud Cort of 10 years ago. Or the Jerry Lewis of 30 years ago. Busey, identified as a self-supporting college freshman in his 20s, recommends himself as more of a man and a nicer guy than Calvin's vainglorious numbskull. He doesn't look right when called upon to be overwhelmed by a rug shampooer or fly through a stained-glass window trying to bust up a marriage ceremony.

The material is so clumsily organized that even this spectacular climactic crash comes as an anticlimax, the heroine having sensibly changed her mind at the altar anyway as we always knew she would. That shattered glass does nothing but throw doubt on the hero's sanity.

A good deal of potential humor is never realized: the rapport between the leads; the idea of Leachman and O'Toole as mother and daughter, which looks convincing enough; and Tony Randall's bit as an irritable butler who's also Leachman's clandestine lover, a gag that certainly deserves more than the fleeting attention it gets.

No one expects "Foolin' Around" to be serious. It comes a cropper by blundering around at the task of being effectively playful.