How to diagnois problem
1996 Pontiac Grand Am with a 3.1. The engine starts perfectly, but after 10-30 seconds the RPM's start to surge up and down. This behavior doesn't stop for 5-10 minutes and then it dies. I did a test I found on line and the crank sensor tested OK. (the only one I could find was a "no engine start" test). We checked the wires for breaks, but found nothing.