vectra

got a mate of mine and he has a 1.8 vectra. when he gets to about 3k revs it goes lumpy and horrid ? anyone know the cause. It gets a fault code of 0505 which is throttle body but we have replaced it with new and still getting fault. Help guys Dann

maybe its the airflow censor? could be manything if it says its the throttle than it will have to be some thign to do with the inlet check for any cracks aswell as the accelerator cable

check the mass airflow sensor if not disconnect the cat and try then reving it then the cat maybe blocked