Could be a fuel filter as well. If you are not getting a pressured system, either pump is not working right or something is blocking it from getting to the engine. That inline unit may be having fits. Also could be an intermittent grounding problem with the pump. Easiest way to check is wait until you have the problem, disconnect fuel line, put a catch can at the disconnect and turn on the ignition. Should hear the pump buzzing and you should see gas spitting into the catch can at a high rate of flow. Be sure to take care with the obvious burn-down-the-truck issues. Have someone help you with the check.

A lot of guys here in salt land have problems at about 10 years vehicle age due to rotting out tops of gas tanks, specifically at the fitting for the pump and sending unit. Not unusual to see the wiring got to pot as well as the metal. Bad grounds can really raise havoc.