Just bought my B8. I love the car. After one week of driving I have a check light!! Code is p0303!!! Already tried spark plug and coil. Light Is still on and runs rough at idle. Reading that there are soooo many opinions of what the heck it is. Icm. Injector. Harness. The list goes on. Does anyone know the most common fix!! Just want to enjoy my new ride lol.