Rough start & bad performance

[FknLoco]

I have a 94 XLT 5spd that recently I reset the comp on it & have replaced the plugs on. After I reset the computer the truck has been slowly losing power & starting worse & worse. It takes 2 or 3 times to get it cranked where it will run & then when you take off it stumbles alot. Once going along even after hot it has horrible low end, mid range is fine & upper end starts to break up, if you hit WOT the truck slows dramatically. I am really confused at what is going on with the truck, I have had the codes checked & only the Neutral saftey switch, which I thoughtt was on an auto only. Any help would be appreciated, truck gets really slow when I load 400lbs of tools in it LOL.

 

[MrShorty]

Neutral position switch code applies to a manual transmission as well. It's usually set from running the self-test with the transmission in gear (computer expects to see the transmission in neutral).
What does the fuel pressure look like?