I, have the same problem does your engine light flash mines a 03 a4, and it says that cylinder one is misfiring, and i tried switching around the coils, and the misfire didnt move also the bolts on the turbo exhaust manifold were loose, and i tightened them down but think the gasket was blown out in the process, and also my cat is making noise could any of these problems cause the misfire, and what should i do about correcting this misfire thats cause it to loose power on the bottom end.... HELP!!!