I have a 1990 Audi V8 and my car is having similar symptoms. My car has little acceleration and idles extremely rough too. It feels like I am only running on half the cylinders. Any time I give the car gas it chugs and sputters like the TPS is failing. Timing belt was replaced about 2 years ago and O2 sensor 1 year ago. I replaced the OSV and am still stumped...

I am thinking that the base timing is not correct, TPS, or the fuel pump is failing on me.