When I'm idling, the car sometimes revs between 500-1000 rpm, over and over again until i start moving. It generally only happens when the A/C is on....
engine revs up and down when idling, only when A/C is on on 2002 Chevrolet Cavalier
this may be normal as the idle will kick up when the ac compressor cycles on and off.
You could have a vacuum leak or the fans are not working. The fuse box in the engine compartment left fender there is a relay for the A/C and one for the heater fan. The one for the A/C controls the fans. Switch the A/C and blower motor relays, turn on A/C, If the fans come on the relay will cost about $10 .