any ford dealer techs out there

I have ran across this same type of issue on a customers mustang, same year and a 4.0. What I found were two loose grounds at the core support, causing an intermittant stall among other strange things. Also, after monitoring the fuel pressure, I also noticed it would fluctuate between 55psi and fall to aroound 25psi than stumble and die while stopped. It ended up being the fuel pump driver module which is located inside the spare tire well. Just some food for thought.