I have an '05 quad cab that has been throwing P0300 multiple misfire codes. After some research I tried testing the fuel pressure and it's zero or very low. The OBD reader does not register a reading either, but the truck runs. Not well, but it runs. Next I checked the throttle position sensor and that sees to be fine. I suspect a dying fuel pump. Any other suggestions?

 

if the fuel pressure is low; check the power and grd wiring to the pump for resistance...if ok replace the pump