I have a 96 Oldsmobile Aurora that has 3 issues:
*The headlight flicker off and on even when the key is not in the ignition. I changed the headlight sentinel module and it didn’t help.
*The air conditioner blows hot air occasionally even after I changed the condensor.
*The engine races up to about 3000 RPMS and when shifted to neutral races up to 4000 RPMS (also only occasionally). Sometimes shutting the engine off and starting it up again fixes it; sometimes not.
Could this be a vacuum leak?
Well, there is an aurora specialty board with a lot of helpful information on common problems.
http://www.aurorah.proboards47.com/index.cgi
The first thing you should really do is check for codes. Also most of this requires use of a tech 1 tool which would be a dealer diagnosis. But the intake manifold bolts should be snugged down to make sure its not leaking air. The multifunction switch is a problem area if I remember right and could cause both the light and the idle problem actually. There is a procedure to clean the contacts on the board mentioned above somewhere. There is also an idle learn procedure to restore idle settings after replacing the idle air control. Goes something like warm it up, let it idle for 5 minutes, raise the rpm over 1500 for two minutes, put the brake on and move in to gear, and let it idle two minutes. I’d have to check the exact procedure but it is buried in the factory manual under drivabilty problems.
At any rate check codes, check IAC, check the idle control module, for starters.