I'm thinking its all of the above. I have been having an intermittent problem with my truck shutting off for a few seconds then running when I'm on the interstate, my fuel tank is not venting properly, and its the original lift pump with over 200k on it.The last three times I filled up was from different fuel stations and I know when I did my head gasket 3yrs ago I dented the aluminum on the heater probably shortening its life. I have been wanting to take the bed off and sand blasting and paint the frame. Maybe I can make that this summers project and I can put the larger fuel lines in and clean the tank at the same time. If the fuel shut off solenoid is bad I'm going to cable shut down also.