the car is fine untill i put the footdown and it gets to about 2500-3000 rpm then it kind ofs judders then the engine mang light comes on and it runs rough but if i turn it off and on its fine ? noticed the other day that smoke was cuming from my manifold when i rev it hard do you think the gasket could be gone and that could mess up my emisions and put the light on ? (mk4 gsi 2003)