2002 Pontiac Montana • 6 cylinder 2WD Automatic • 87,000 miles

My 2002 pontiac montana has been hesitating, misses and stalling. Would a TPS sensor cause this? I've replaced the preconverter o2 sensor ( the one that affects pcm and air/fuel ratio) and still problems. Heres the thing it runs fine until it warms up. I can rev it in park and its fine warm. I go to test it and drive down the road and starts all over again. If I dont accelerate too much I can make it back home. Would the post converter cause this problem? I hooked up a scan tool and read the parameters to the postconverter o2 sensor and the voltages aren't what the car manual says. It says it should hover around 0.40 volts and change slightly however my readings indicate that its around.59 and when I accelerate it goes below 0.40 volts. Is this normal or is it something else as the price of an o2 sensor is $150 and I already bought the wrong one! Thanks
December 20, 2010.

A bad Tps sensor usually makes the rpm's bounce around. Is there a MIL light on?

Dec 20, 2010.
Your really going to waste a lot of money here approaching this in this manor. There are dozens of things that can cause symptoms as you describe but the 0/2 sensors are not one of them. The rear sensors have no effect on engine performance at all. This could be a bad mass Air Flow sensor but I still wouldn't replace it without some testing to verify it first.

Dec 20, 2010.