My money is on Fuelfilter and or Fuelpessureregulator. (plugged or weaken)

 

I had the same thing happen to my 88 bronco. Ran fine at idle and light load, but as soon as it had a heavy load or was at faster speeds, it would stall out or sputter bad....let off the gas and it would idle right back up and run until I got on the gas again. The fuel filter was partially plugged and there was more junk in the fuel line. Every time the engine would require more fuel, it couldn't get it and would die or sputter. The times it died, I would pull off the side of the road, wait a few mins for the fuel to go back to the tank, which it would take some of the junk with it, and then it would start back up and run fine till it sucked more junk up. Hopefully it is the fuel filter just because of cost, but there is a possibility of the maf being bad too. Keep us posted as to what you find out.

 

we got stuff in the airport follow-me truck's gas tank from as my supervisor put it "Sabotage". but, back to the matter at hand, I think its the fuel pump/filter/lines just like in yota's bronco