I have a A4 2.8 Quattro and i am getting codes p0300 and all the other ones for all 6 cylinders, I have replaced the coil pack and all the plugs. It is mainly misfiring at around 4000 rpm and it will start the check engine light to flashing but then will stop and not come back on but the codes are in the computer as pending , in park if i rev the engine to about 1500 rpm it will go up and down about 500 rpm