This week, the California teen-ager slipped all the way to No. 4, but the chart champ is still a Shondells remake. That's because Billy Idol's version of "Mony, Mony" had just enough momentum left to slip into the top spot ahead of the Bill Medley-Jennifer Warnes duet "The Time of My Life" (up from No. 3 to No. 2), which is already No. 1 in radio airplay and on the adult-contemporary chart.