This has been happening for the past 3 months off and on and I've yet to determine exactly why it's happening and would appreciate some assistance if anyone has advice. On a regular drive I can produce ~30+ some odd pounds of boost, but about every 3rd day or so this number drops to ~25 and I notice a slight loss in low end power while driving around town. This power loss will continue until magically another day I'll regain my power and boost without changing or modifying ANYTHING on the truck, fillup on different fuel included. So far I've:

Pressurized tank and checked for air leaks: none found
Changed fuel filter
Removed/Cleaned injectors

Could this be a symptom of a faulty lift pump? Any other ideas?

 

How's the throttle linkage? Sloppy bellcrank bushings?

I'd throw a lift pump at it and look at the fuel pickup if that doesn't cure it.

 

Do you or does anyone have a picture of what exactly the bellcrank bushings are? I'm getting near full travel with pedal to the floor but I think I'm missing something .. replacement lift pump is in transit

 

The bellcrank is the part between the accelerator cable and the throttle rod. It rides in plastic bushings. If those are sloppy it can move all over the place and give you inconsistent throttle operation.

 

Possibly you could also check your fuel pin inside the pump (the one that rides on the cone)..it could be sticking in and not allowing any fuel under low boost?..

 

Plus 1 If you have an aftermarket one especially. Some have found that they are making the pins to soft and they get stuck.