I'm having an issue whereby the motor drops revs very briefly and then rebounds. Happens every few minutes independent of AC or accessory operation. Last week I noticed the dash lights would dim just before the revs dropped. Shop foreman immediately diagnosed it as a bad alternator and replaced it. The readings were 10.5 volts over 8 amps, and he said it should read 13.5 over 80 amps. So the alternator was failing, but the car still does this, though not as often. I don't have any ideas.