JJENS

This buzzing is driving me insane! It only happens while driving and in gear...coasting in neutral and accelerating to this RPM range does not replicate the buzz. Nothing on the dash seems to be loose. The dealership said they thought it was the charge air cooler tube...this makes no sense to me. It sounds like it is directly behind the tach and not muffled as if it is in the engine compartment. Please help!