I have a 2003 Audi A4 Quattro itís the wagon with a 1.8L turbo. I have an issue I canít figure out I have multiple misfires and I believe one of my cylinders is completely dead. I have already replaced spark plugs and the coil pack leading me to believe that the issue could be vacuum related. My ac and heat does not work and it only blows from the defroster vent. It also idles very rough any ideas as to what could be causing this?