The first thing you need to check is fuel pressure. It sounds like you may have a clogged pickup line in your fuel tank. If you dont have access to a FP test gauge than I would recommend blowing pressurized air back thrue the feed line going from the tank to clear any debri. This will only by temporary and if that is the problem than I would recommend doing the fuel tank mod that a lot of guys do.
1994 f250 4x4 exc lb 7.3 powerstroke zf5 speed 378k 3.55 gearing 10.25 sterling LS rear axle, dana 50 ttb front axle, 235/85r16 cooper's
Napa 6637 air filter, 120v idm, everything else is stock.