No codes

[Mikanic]

I am leaning towards something on the suction side of the fuel system.

To quickly check if your lift pump is pushing pressure you can push with a small screwdriver on the center of the compucheck fitting right above the secondary fuel filter, on the filter housing. It's usually covered by a red condom.

BEFORE YOU START the truck check your primary filter for air if you have the Paccar style with the clear bowl at the bottom, it would be an indication its drawing air in the system. If you see a separation of air and fuel you have an issue somewhere on the suction side of the fuel system. I have seen these types of filter housing draw air and cause problems when they get corroded and old.

If you have a Davco filter with the clear bowl on top is the fuel level at the usual level in the housing or is it completely bellow the bottom of the bowl?

Did the issue start shortly after replacing the fuel filters?
Did you replace the fuel filters since the issue started?
stuff I would ask you if you would be a customer at my shop