I'm hoping someone can really help me here. I am about at my wits end.

My truck started chugging, sputtering, and then dying about 6 months ago. It was initially acting like a fuel problem, but the pump was replaced 1 year ago. Symptoms are that while you hold the throttle steady the RPM will go up and down, surging basically. It barely holds idle, and when you put it in gear pretty much dies. The strange part is it is intermittent, it will act up, so I play around with it, or let the truck sit, and it might drive perfect for a week, then comes back.

I have replaced the TPS, MAP, O2, Fuel Pressure reg, and ECM, but its still doing it. If I put a vaccum pump on the FuelPresReg, and pump it to about 5-7 on the gauge, it idles better and is drivable. It has proper fuel pressure when I tested it at the beginning of my saga. The pressure regulator is hooked to a vacumn line that is above the throttle plate as I see it. If I put it on a hose below the throttle plate it seems to like it better. (Forgive me but the terminology for the two escapes me). I am about to go through all the vacumn lines, but from what I can see I dont have a leak anywhere. All the other vacumn dependant items seem to be working fine.

Any thoughts? Please?

 

Forgot to mention, new cap, rotor, pickup.

 

I know you tested the pressure in the beginning but have you done it lately or when it runs better with the vacuum on the pressure port.

 

Im going to have to go rent the tester again. My other thought is to test the voltage to the pump.