1991 F250 7.5l EFI loss of power under demand

[Luggingalong]

Pulling a grade yesterday and lost power big time , nothing over 2500 RPM . Even when I limped too the top of the grade onto level ground . Only after I babied it home cooled it with water over the radiator , turned it off and let it set 10 minutes . Then fired it up and revved it a couple of times did it finally kick up past 4K RPM . Question ; O2 , MAP sensors injectors or fuel filter or pump ?. Where would you start to look for the problem ?. Truck was warmer than normal when running extremely dry air 7-9 % humidity but never got close to boiling over . it's normal temp position is between cold and half , yesterday it was half way straight up . Thanks Luggingalong

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