I have a 1999 Pontiac Montana, It started having idle problems and hesitation in park and drive. I replace the lower intake about 6 month ago along with the upper intake and tons of O-rings. Now this started I have already tried new plugs, wire set, fuel pressure regulator, map sensor, installed all new O-rings on the fuel injection rail and injectors, cleaned the MAF, new air filter. I checked for fuel pressure and spark coming from coils. Everything is firing. It starts easy. I figured a vacuum leak so I sprayed everything down while vehicle is running. I found one little spot that it made it changed idle but nothing really noticeable. I will address this too with new upper intake gasket. I have unplugged the EGR and throttle position sensor no change in idle at all. Pulled the MAF and vehicle will cut off so thats working. I have no check engine light on and has never come on since we have owned it. It has 145,000 miles. Could it be a faulty PCM or a burnt valve? This is about all I can come up with except maybe cam sensor and crank shaft sensor also.
Tuesday, May 15th, 2012 AT 2:04 AM