A4 B7 Avant 2.0 tfsi - I recently ran my fuel tank almost completely empty. After refueling, I drove a short distance and then the engine starting running rough and the check engine light came on and flashed for 60 sec, then stayed on solid. I think that debris from the bottom of the tank made it past the filter and has clogged the fuel injector on cylinder 4. I'm getting code p0304(cylinder 4 misfire)& p0171(system too lean bank 1). Im going to replace the fuel filter 1st. Is there any way to clean injector 4? If not, what is the procedure to clear the fuel lines of debris before replacing the injectors?