I have a 1989 f150 the truck has sat for 7 years and I got it running really well except when I go to give it large throttle like getting on the interstate it just makes funny poping noses and will not pick up speed but it idles like it should checked fuel press and its about 35 when I unplug the regulator vac line it goes to 43 and seems to run better and throttle better is my fuel press regulator in need of replacement

 

Your fuel pressure is fine, assuming you don't have the 4.9L I-6.

How is your ignition? New plugs, plug wires, cap and rotor, or the seven-year-old (or more) ones that were on it when you got it?

 

no I have all new cap rotor plugs and wires the only thing I thought that was odd is there is no fuel filter that I can find the lines go from tank to switch valve to pump then to engine and the engine is a 5.0 im thinking about eliminating the switch valve and replacing it with just an in line filter and also eliminating my rear fuel tank my return lines I have a piece of plastic tubing that will hook them back together

 

Any codes stored in the PCM/ECM?

Similar problem for a friend ended up being EVR solenoid..but this was shown as a stored code.

 

Is your egr and vac lines good mine vac line to egr was broke and also had to replace egr position sensor and evr solenoid. Scrobbie

 

Maybe check the IAC or catalytic conv? It might be stuck open, running a little lean, back firing through intake. Mine did that when I'd give it gas to accelerate. I "cleaned" my cat and IAC and it no longer does that.

Just a thought