I have an '04 Pontiac Grand Prix GTP, and have had the same problems. When they started, I cleaned the injectors, changed the plugs, wires, air filter and fuel filter. Ran better for about 2 weeks, then got worse. Added fuel injector cleaner, and saw no change. Took it to a garage, and they changed 2 of the ignition control modules. Improved again for about a week, but now I am back to the beginning. Sorry - I know it doesn't help fix your problem, but might help you avoid adding all of this cost for nothing.
Thursday, May 31st, 2007 AT 9:41 AM