I have a 96 3.8 that just developrd a bad rap the intake gaskets were bad and it sounds as though is is comming from the upper end. I have removed the valve covers and intake I doo not see any reason for the rap yet it also rolls over hard when it was together I lost power but rolles over normal now that it is appart. Could it be a cam bearing or broken valve also when running the noise was not consitant it would come and go and changer speed and valume??