I have a 2000 GTP. The Check Engine Light would occasionally come on due to misfire Cyl 4. After a while, the light would stay on and flash. Bad news there, as I was on a trip one time in an Isuzu (they were in cahoots with GM) and the light went flashing too. A coil was bad, and raw gas poured into the RH cat melting it.The back pressure ruined some valves, and I ended up with a new engine.
I ordered a coil for the Pontiac, installed it, but no joy. It occurred to me then that I should've checked out the injector. I got out mechanic's stethoscope, and listened to the injectors by placing the metal rod on the connector. I could clearly hear the click click click as the injector cycled, on all injectors except number 4. Four was totally dead. So I ordered a new injector on the 'net, and I'll pick up a set of O-rings from Oreilly's for that side of the fuel rail. I should've done that before I ordered the coil. Oh well, I have a spare coil now
