02 sable w/ 3.0 sohc... once warm with the a/c or heat on the rpms flucuate by about 300-400 rpm. the idle air control checks good and was cleaned. i have checked all vacuum lines and all appear good. i would think if it were vacuum it would do it all the time but im no expert. can the compressor be causing this problem? any suggestions would be greatly appreciated as ive read about this problem before but ive never found any definitive results. Thanks!!