Sorry dude, I have the 2.5 duratec. mtx with 77000 miles. With the four cyl. I would use the long screwdriver or hollow 1" pvc poipe test and listen to where the sound comes from. I've had a slapping noise from a frayed belt before. Unfortunately it was a timing belt and it snapped and toasted the head. Also check for loose spark plugs.
Good luck
