FIXED. In case anyone is interested in this reported problem.... The problem was with the harmonic balancer, specifically with the steel rings attached to the rear of the balancer that have "teeth" that are used to trigger the CPK sensor. There were two missing screws (of 4) and the remaining hold d...

GM 3800 supercharged year 2000 Pontiac Grand Prix GTP. Engine starts and runs but struggles to keep a stable idle speed, RPM varying from 1500 down to 600 and back up until gradually stalling out. It will re-start with no problem and engine can be kept running with throttle assist but still has an a...