Not getting enough fuel pressure? 88 f-150?

i have an 88 f-150 and i believe it is not getting enough fuel pressure...i have not put a tester on it considering they are 50$ so im trying to eliminate some other things first..so i just got this truck running after sitting for 4 yrs...ive replaced spark plugs,wires,fuel pump,strainer,fuel filter,fixed a leak from the "fuel vapor canister?'' and have also been running cleaners in through it such as sea foam and lucas injector cleaner...so i go out and work on it just about everyday after school and i have to use starting fluid every time and it takes more than one try with that...also i finally drove it yesterday and at a steady throttle in gear,driving,and it was jumping around as if i was flooring it and letting off and so on...and in neutral it will idle but only rev to almost 4000...and on the side of that my fuel guage doesn't work either ....and thoughts of what it could be? or what to check? ...and it is fuel injected and also a cobra block,internals,and headers,so its basically whole cobra motor minus the heads and intake