Ok I'm having a fuel supply issue iv deleted front tank blocked the lines off. Iv replaced fp, and ff, truck only lets me drive at 1/8th throttle before chugging and surging yes I replaced tps and map and iac and tb, I have headers and straight pipes the weird part is if I hit my switch on the dash to front fuel tank and quickly switch it back to rear all problems go away for a few minutes and then I must repeatedly switch tanks in order to be able to drive at highway speeds or uphill please help me. PNW oregon area..
91 f250 7.5l E40d

 

I see you've replaced a bunch of components, but have you tested any of the components? Have you done a fuel pressure check? Have you checked for engine codes? Have you used an ohm meter and checked the TPS? Do you have any exhaust leaks before the O2 sensor? You should also check your ECT and IAT with an ohm meter.

 

yes iv tested the fuel pressure it sets at about 40 to 45 koeo and running at 55 sometimes a little higher when i go wot it falls about ten psi and when i push the fuel pressire bleed off seems i get alot of air and the i believe its a fuel check valve on top of my fuel pump I can blow air through it both directions my map is good tps is set at .8 and fuel pumps good why would flipping the selector switch take away the problem momentarily or a few minutes and truck runs primo?

 

Something is wrong. Youre fuel pressure it too high. And your fuel pressure should never drop when you go WOT.
Good observation with the Fuel tank selector switch. You have a 1991, so you should have no selector valve, just fuel selector switch which runs individual fuel pumps. You maybe be sucking a vacuum on your fuel tanks. Try taking your gas caps off and doing a test drive. When your truck is running bad, what happens if you switch to the opposite tank, and then immediately back to the same tank?

 

Answered in the first post. Could the high pressure be from how the OP capped off the deleted tank?

OP, I fixed that transmission abbreviation for you. That’s an “oh” as in OverDrive

 

I forgot in his first post, the first sentence mentions that one of the fuel tanks were deleted.
The fuel tank delete would be my prime suspect. First thing I would do is to remove fuel cap, then remove the return fuel lines from the fuel rail, and then blow compressed air through the return line to make sure it's hissing in the tank and has good flow. You'll probably find out its clogged, or it was improperly capped, or double-backed on itself.