Got my car back today.
The car runs fine now that the enginewiring has been changed. (Fingers crossed). It seems more wiling to take revs now and the exhaust sounds more muted.
I also mentioned the throttle potentiometer, but they said that faults like this is often confused with ecu and induction-problems.The chief mechanic seemed very confident that nothing was wrong with either of these.
They scratched my left fender when the car was in the shop though