Back to the original question:

Sounds like there might be something binding up in the accelerator linkage or maybe even in the pump. That would be the first thing I looked at, maybe the fuel filters too but that sounds unlikely.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k