The car is fine up til 5500 rpm the the power just drops off, like a deisel does. It drives 100% fine apart from that. It only does this under load. it revs fine when at a stand still.

Checked the throttle cable. Had the lamda switched off in the ecu. Still the same.

Fitted a BD10 exhaust cam a little while ago, could that effect it like that if it was wrong? The cam timing seems is right and had a few people check it, maybe its a dodgy cam?