Hi
I had a very similar problem with a 2004 zetec 4/4 , misfire ,engine stalling, had it checked at a ford dealership but nothing showed on the diagnostics as it was an intermitant problem,it turned out to be a faulty fuel pump relay!
That is a good call. I always now carry a spare relay which can be used either for the fuel pump, or the cooling fan; having had one fail in the past. Also, very easy to check.
