PLEASE HELP!!!!!! I have a 1987 F-150 that will not stay running! It starts up but only runs for a min or so. I have replaced the wiring harness, fuel pump, and fuel regulator.

check fuel filter if it has over 75,000 miles it needs changed, need more info like how many miles on your truck, do you drive it low on gas like near 1/4 or less a lot. that will cause fuel filter to clog, air filter too need changed ever 2 years

Forgot to put that we changed the filter too. It's getting has but won't stay runing. It has 2 tanks a reseved and a regular one. We filled them both up half way thinking that the tanks wouldent switch over but that's not it. It's getting gas.

I would start simple with plugs wires cap n rotor, it is no good to change one thing with out changing them all, make sure the plug gap is right cause they are never just out of the box.

Okay! I'll check tomorrow thank you so much for your help!