P0171 p0174
I replaced the fuel filter because it was plugged and no service record of it being changed. (Have all kinds of records)
Fuel gauge shows 32psi while running and when it dies jumps to 35psi.
Unplug the fpr fuel pressure goes up.
Haven't checked the pcv system yet but no hissing

 

I had a bad O2 sensor in the exhaust that threw lean codes and made mine feel like it was missing on a cylinder...

 

I'd bet it's a crack in your PCV elbow. Sometimes you have to get your hand back there by the elbow to hear it.

 

So much easier to just swap in the 5.4 now and fix that while I'm at it