Q: Sputtering, misfiring, power loss and gain

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My car has the 3.4L when it warms up it misfires power goes in and out and when you give it more than 1/4 throttle it acts like it either gets to much or not enough gas and when it hits overdrive it shutters. What could the problem be?

My car has 217000 miles.
My car has an automatic transmission.

Hey there:

There are usually two different mechanical problems that cause the symptoms you’re describing with your Pontiac Firebird. The first and most common is a problem with the ignition coil, (especially in mid-90’s GM V-6 engines) or due to problems with fuel injectors that are dirty or corroded with excess carbon buildup from the EGR system.

If the Check Engine Light has illuminated on the dashboard, a good bet would be to contact one of our local ASE certified mechanics who can download any error codes stored in the computer which will give them a good indication as to what’s causing your engine misfire.

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