i have a 97 lumina 91,000 miles on a 3.1l v6. car runs great when cold, after it warms up it starts to miss/hessiatate under load. things i have changed or rulled out. new plugs, new wires, changed oil and filter, new fuel filter, checked fuel pressure and doesnt drop below 40psi while driving, checked back pressure on exhaust in case cat was plugged and it is within normal spec. i am at a loss. there are no check engine lights on and no codes. also the scanner shows no miss fires. you really noticeit when it is trying to shift into the next gear like first to second and you have to full throttle it to get it to go. please help. i need this car fixed!!!



thanks brandon

 

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What has changed to start this condition?

 

bought the car this way. figured it was something simple. guy never did any tune up item. so i did it all and still no change. thinking maybe something to do with coils or ignition when it warms up. not sure