X15 Efficiency dies for no reason

[ElgatoCatfish]

This truck had a dd15 and now had a x15 efficiency and ran pretty well until a service was done by a shop in west texas. Since the ive replaced fuel pump check valve on fuel rail and sensor. If I drive the dawg out it no problem. Soon as I park it might idle 30 min 1 time. 20 the next and sometime just maybe 2 min. Shut the power switch off and wait 20 seconds for the lift pump to prime up a but and boom she fires right up like perfect. When it dies start to die it sounds like it's running out of fuel. No codes though. I'm lost. I've replace the davco housing. Fuel lines, and the main fuel filter housing still no joy. The oldnschool cummins guy in Illinois is telling me to replace the lift pump blowback check valve and the fuel metering /cut off valve on back of HP fuel pump that had the 2 wires. Please any ideas would be greatly appreciated