I have a scanner but it only pulls codes and tells you what that code is. I dont have access to nice scanner. Although a few months ago I told the other half I wanted a really good scanner LOL. She should have listened.
I have a cheapo and an old MTG2500 SnapOn scanner. I was trying to be lazy and use the cheapo but was getting no where. I broke out the MTG and it zeroed in on the problem on the first run through.
The old valve in head 4.0L had head gasket and/or head issues but I don't know about the SOHC engines.
I would get on the Ford forums and start asking questions.