2002 7.3 wont start!

[rj9688]

I need some help on figuring out whats going with my 02 350 with aprox 110k miles.

This issue has been coming and going for almost 2 years now. the truck will absolutely not start unless its plugged in or had been ran within 4 hours or so. we have changed glow plugs, glow plug relay, wiring harness, bats (twice during the last two years), injector drivers, and the #5 injector. If im lucky and it does start not plugged in it acts like it is having rpm surges (going for almost dying to 1100 or so), when its doing this it has a moderate amount of black smoke coming form the exhaust (this occurs when its surging and at the point it almost dies). the surging usally clears up after 1 to 2 min, or when you rev it up to 1500 and then let it return to idle, or when the temp gauge begins to move from cold. it never does this if its plugged in for more than 2 to 3 hours. basically if its plugged in for 2 hours it starts and runs like it did when we bought it, with no power lost. the problems orginally occured only during cooler days (65 and below) but it has progressive gotten worse and now it has not started on days it was over 90.

The truck has looked at by 3 local Ford dealers one keeping it for over 4 months and the other for over 2, to only have the problem keep coming back.
i have been told that it sounds like my injectors are sticking closed, however when checked them the only one that was even close to being bad was the #5 and we changed it, i have also been told that it might losing fuel presure in the lines while it sits for an extended time (i have never heard of this and dont know how to check for it), the last thing ford told me was they dont why its doing it and i need to just by a new $13,000 motor from them and thats the only way they could fix it. it doesnt use oil, has very little if any blow by, and has no noticeable power change.

any sugestions on what might be causing it, or maybe ways to fix would be greatly welcomed. thank you in advance.