Got a 91 f150 300 and its been wanting to stall at lower rpms and loses power at driving speeds. I pulled codes only thing that came up was EGR but when I tested the valve it showed working. Did a fule pressure test and the gauge read 40psi at key on. Engine running made the gauge bounce back and forth from 45 to 25 really fast and erratic. Need to know my next move, fuel pump? Fuel pressure regulator? Donny see any breaks in the line and doesn't leak fuel. Rear tank isn't in business so can't test it on that. Any help or words of advice will be greatly appreciated

 

Check for vacuum leaks, which may affect the fuel regulator on the fuel rail?
Replace the fuel filer?

Do you have a Fuel Pump inside of the tank? or is there a spaghetti of hoses hooked to an octopus looking thing in the frame rails, that was used on some early EFI's with dual fuel tanks. I don't know what it's for but it looked complicated and I passed on those years when I retrofit my '78. I like the KISS thing, even though I made my '78 overly complicated

 

Yes I replaced the fuel filter and ended up purchasing the regulator on the rail. I will be replacing that tonight finger crossed! It does have the internal fuel pump. I guess if this doesn't work I will be traveling there next