TOUR DE FARCE

''Spontaneously'' written and performed by the late Jeffrey Strouth from the back seat of an old car, american fabulous (1992, First Run, $59.95, unrated) is one unusual achievement. In telling his life story, the sardonic, witty, and abrasive Ohio-born monologuist-a flamboyant cross between Clifton Webb, Tallulah Bankhead, and William S. Burroughs-is uncommonly entertaining and just a little frightening. A