Some questions:
- How many miles on the truck?
- Are these the same miles that are on the injectors / injector pump / and fuel pressure regulator?
- Is the check engine light illuminated? If so, what are the codes retrieved?
- Any smoke at the exhaust under acceleration?
It sounds like a fuel delivery problem. Since you have effectively eliminated fuel filter restriction as a problem, it points to fuel or fuel delivery componants.
- Any chance that your last fillup wasn't #2 diesel, but unleaded gasoline? How many gallons of fuel did you add, 100 miles before the problems started? Was it at a BP station, with the dreaded green handles? I have made this mistake once, to the tune of ~24 gallons unleaded fuel on top of the remain ~8 gallons of diesel. I drove the truck for almost 80 miles before first noticing the problem after the first stop. My first thought was a plugged fuel filter, I didn't even notice the gassy smell until I replaced the filter and the truck would not easily restart. Also - the truck had very little power once stopped, but would run fine once up to speed - i.e. under minimal acceleration load. Check your last fill receipt to verify the cost/gallon you were charged, if you still have it. Also you can drain some fuel from the petcock on the bottom of the fuel filter and smell it;
If you are sure that you have good #2 diesel in the tank, AND there is no odd smoke at your tailpipe, you may be experiencing the failure of the high pressure (injector) pump, but that would probably be setting some codes and the Check Engine light.