Idle fluctuates between 500-1500 RPM when stopped. It also may stall.

Google > how to get obd 1 codes from GM vehicles .. On the results page you should see a video link to YouTube plus a diagram showing how to do this .. It's very easy to do then you can post the codes here for more help .. That will cut 'way down' on the guess work!

We are in South Plainfield not too far from you. We can definitely help you if they can not find the problem. Cars new or old can all be fixed. Mitch