After a tuv visit, cars run badly…..

I have recently been at the TüvDekra , now shortly afterwards I noticed that the car is driving totally sluggish from 1800upm he otherwise pulled very well up to 2200 now somehow nothing more gurgles just around. Had seen the Tüvprüfer has there also something groped around on the engine . Can he have changed something there ? or what check those on the engine ? what could that be?