My 2006 cobalt ss has an unknown tune an it misfires over half throttle or 20kpa boos
 

Hey guys i have a supercharged cobalt with the 2.0 engine in it. I bought it off someone and it misfires when i step on it over half throttle or if the boost goes over 20kpa. I just put 4 new plugs in them and when i tried it out the misfire was gone and i took off like a jet down the road. But after i stopped and took off again it gave to much fuel or air again and fouled the brand new plugs right away. Does anyone know what i should try next? Thanks in advance!

what plugs did you put in it? what did you gap them at?

what mods are done to the car? what size blower pulley?

^^ The above questions plus I am guessing your CEL light is on and if so what all trouble codes are set?

If you're running super rich, then it might be something with the tunes fuel calibration or you have a mechanical problem that caused the tune to become rich. You'll need to see what your AFR is doing with a wideband air fuel meter to see if you need to make adjustments. For now you'll need to check for mechanical problems between the air filter and muffler.