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

 

Did you pull any fault codes?
Does your car have any mods?

 

It does and they are all accounted for in the tune. It’s showing random misfire and misfire on 4 and 8. It sat for a year and was rebuilt. I’m looking at changing the manifold and the emissions canister

 

Are you looking to replace those parts because there's something that points to them or what?

 

You said it sat for a year after being rebuilt for the blown engine. Did you do the crank relearn process when you reassembled it? If not, that is probably the cause of your misfire. One of the symptoms of an engine and transmission put back together without doing the relearn is random misfire.

If you have a SCT X4 you can do the relearn yourself.

 

The cam relearn was done. The injectors, spark plugs and coil caps were replaced. I’m changing the intake manifold next