Seems that Ford have very cunningly built that problem into ALL their cars! My wife's daily driver, a 1999 Aussie Ford Fairmont 6-cyl suffered from the same thing just before christmas. Since I fitted a new gasket, and tightened the manifold back up, it has run better than it ever has in the 5 yrs we've owned it. Possibly better even than when it left the factory floor. Believe it ... or not!