The Nick of Time — George Alec Effinger

Time travel: been there, done that or at least Frank Mihalik has. On February 17, 1996, Frank discovers the secret to time-travel, or at least he thought he had. He must embark on a voyage through time and space in order to set things right. He must survive parallel universes in which--Oh my!--Shirley Temple plays the awesome role of Dorothy in "The Wizard of Oz"! Only his love, Cheryl, can save him, but he is almost tricked by a parallel-dimension Cheryl and potentially wrecks his love life. How will Frank survive this wild jerk through these dark counter-universes? And will our universe ever be the same?