Hello, I have a 2011 GT. When I'm at about 3k rpms and I come off of it a little, I have misfires. I have changed the plugs, coil packs and injectors. The car sat for a year with a blown engine and then was rebuilt by a reputable shop. I have had them and 2 other good mechanics try and find the problem with no luck. The car runs great until I come off of it. IA good example would be driving with the cruise control on and when I go down a little hill and it throttles down, that's when it happens. Any help would be greatly appreciated.

 

I know this is going to sound weird, but I just had the same problem, I replaced spark plugs, coils, injectors, and it turned out to be the canister purge valve. I replaced it and I haven’t had any misfires. Hope this helps!

 

But again, I have the 3.7, in which mine sat for 3 weeks at the dealership while they installed a new clutch. After I got it back, I kept getting intermittent misfires on 3 and 4. Mine would happen after I accelerate and let off the gas, or when I was around 80 and downshifted into 5th. When I drove the car, I could feel it losing power in the pedal and then it would misfire. It always happened at high speeds. I replaced the spark plugs twice, coil packs, injectors, MAFS, checked for vacuum leaks. I chased this misfire for a good month. Then when I changed the canister purge valve, I haven’t had a misfire since. The car runs great now. This fixed my issue, hope it is some help!

 

GtMichael welcome to the forum but please take time to learn the sections. This section is for It isn't for questions about your car. There is a section for every model year.

 

Sorry about that.