i need help asap. u can see what mods i have in my sig, and going on that and the condidtions i'm about to describe can somebody please point me in the right direction. anywhere from 1%-50% throttle above 2000 rpm's, my car runs smooth. but once i try to punch it, and give a little show of power, my car sputters and jumps like it's misfiring, and backfires a lot! when i change gears under normal driving conditions, and give normal throttle (what used to be normal), it acts like it's gonna stall out and jumps. do i need a simple tune-up...or do i just need a good dyno tune??? thanks guys!