i drive a 04 gti 1.8t, its giac tuned, nuespeed fmic, forge dv, 3in turboback exhaust, and cai. my check engine light will come on, and then it will go away every couple of days. took it local dealership and got no answers. dont know much about vw's so any advice would be helpfull, and if you know the problem will pay you to show\help me fix it. THANKS

Nick