We have a 2008 F8 that has a very intermittent stall. Will start cold normally, and may run perfectly for 100 miles. Shut it off for 5 minutes, drive about 20 feet and sometimes it stalls. Will restart immediately, and will run until you shut it off again. Sometimes it will have a hesitation, or a bog, but has never quit and not restarted. Put a fuel pressure gage on it and will maintain 40 psi at all times, and will hold that for days. We have repaired a few bare wires, changed a few parts with another machine that runs normally, but it still does the same thing. Exhaust valves are clean and adjusted properly as far as I can tell. Acts like when it starts, during a self check it sees something it doesn't like and turns itself off. It's very intermittent so when we find something wrong and fix it, then it works for a whole trip, we think we got it. Then it will do it again. Any suggestions?