I second the PCV hose. On the Duratec it's a very difficult hose to see, but if you take a flashlight and look through the intake manifold at all angles, you'll see it smashed in there. You can also catch glimpses of it from underneath, but getting your hand in there to feel it is a task fit for Houdini. Ford apparently has a $600 deal on PCV valve and hose replacement, which they do with special tools while the manifold is still in place. Doing it yourself requires removal of the manifold, which is a process.