Hello, I have a 1994 audi 80 sport, engine code ABK. & I have this problem. The engine hesitates/judders on acceleration, at high revs it has no power, at low revs it judders & hesitates intermtantly. It feels like a diesel vehicle in the winter when the fuel 'jelly's-up'. I recently changed the engine & that is when the fault started, so I'm pretty sure that its electrical. my new engine is exactly the same (ABK) but is from an L reg audi 100, my car is an M. I kept the injection manifold & airbox to comply with my cars wiring & plumbing. I have changed the temp* sensors & MAF sensor, the temp* guage does'nt work but it never did. The 'cat' rattles so does anyone know if a damaged catalyst would cause this problem. I am fairly certain that it is electrical becouse sometimes its fine. Any help or advice would be greatly appreciated.