I have 1990 Gxe with 160,000 miles on it, it runs well the only complaint that I have is the RPM drops below one causing the car to vibrate. The air is the main cause of the vibration, when I first turn the air on it wont drop immediately but after riding for a while and I stop at a light that is when the vibration occurs. Stop and go traffic makes it drop severly low and makes it vibrate vigorously. If anybody has any idea what the problem could be any comment would be greatly appreciated. I really love my car and I want to ride it to the wheels fall off.

 

1: do a search & read the FAQ (if possible)

2: As it has to do with the aircon, suspect that area first. Get your system checked to make sure their's no leaks, no restrictions (ie compressor) & you actually have freon (or equivalent) in your system. If you keep running the air, you're gonna kill the compressor real soon.

 

why dont you try setting your idle at a higher rpm. if it only shakes at low rpm's, set the idle to a higher rpm and maybe that could help the problem. (maybe)

 

it seems liek the problem i had before if it occurs like when u are braking like at a stop light i think it could be the distributor / distributor cap. i dunno if it helps but the symptoms u describe are what mine was like when it died. also from what i remember and read before the iacv valve or something liek that may also be the cause. try a search on rough idling etc. and see what u find. its been discussed before. i hope this helps. best of luck.