My Pontiac Aztek is a 2004 has a 3400 in it and it's been running good then all of a sudden I go to drive off and it starts sputtering every now and again backfires when I try to give it gas cranks up idles fine but when I give it gas and it reaches close to 1800 RPM it starts to shut her or hesitate very badly like it's wanting to die but when I let off the gas the revs go back down and it sounds normal what could this be?

Is there any white smoke coming out the exhaust? Sounds like the same problem my friend had when he warped his head on his 91 civic. Any overheating at all? Otherwise another guess would be maybe a bad catalitic converter that clogged up. Hope this helps any, good luck

sounds like the ignition module is going bad.

The first thing you need is to have the unit scanned. Check things like the baro sensor,map sensor,coolant temp. and the TP sensor.Also check your fuel pressure,volume and injector spray pattern. I think you will have found your problem,but if not hit me back with engine size and any codes,Good Luck.

There only one problem wrong.You dont let your transmission warm up.You transmission has you warm up just like the motor.Try this and i promise when you take off it will shift like no other

Check TPS for smooth and linear electrical response over the entire range of motion. If the response is jumpy or erratic at all, replace TPS.
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