After a near impossible SD Header install on my 06 GT i got everything hooked up and started her up... But the engine is shaking pretty bad to the point where you can feel it while sitting in the driver seat. The idle will stay consistent than stumble for a second. The CEL is on but even if it was running fine it would be on because i'm cat-less. I'm to afraid to drive it up to the autoparts store to get the codes read. The seal between the headers and the EGR tube has an exhaust leak but idk if that has anything to do with it.. Any suggestions on what i should look for?