[frankwjr]

Just a thought how many miles? And do you get into it much? If yes then also take a look at your motor mounts...the mod'd TQ on these motors can wear them out...also your clutch...sorry to say...you don't list an upgraded unit so if the flywheel is gettin worn could be losin balance ergo...vibration....good luck!

btw - check ALL the bolts in the entire drive train...