Started as a ticking at cold start and quickly went away leading one to believe it was a lifter problem. While reading a similar forum I saw a post saying to check the rear most upper exhaust manifold bolt that for no reason breaks off. Sure enough it was. Ford Garage quoted me over $600.00 plus time and material for each broken stud they had to replace. I did it myself in 6 hrs and about $150 in parts from advanced auto. The manifold was not rusted through, it was warped bad on the rear cylinder. I do not know how Ford service can sleep at night at that kind of labor rate. Not saying the techs are not good but FMC could stand behind there mistakes and make repairs on obvious defects at least affordable, if not free!!!!