The engine idles rough and rich at start, after engine has warmed up it shuts off

This could be a couple things, but we need to start with monitor the o2 sensor data when the truck starts and then as it warms up, we need to watch them to see if the PCM starts to adjust the fuel trims to compensate the possible rich condition and leans it out and then it will stall.

Basically, there are a number of things that can cause this, but we need to know what the engine is doing to figure out what direction to go.

https://www.2carpros.com/articles/stall-at-idle

We also need to check for codes and find out if there are any. If there are no cords, even if the check engine light is not on, that will be good info.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I am attaching a chart below that will help with determining rich or lean on the fuel trims so let's start with this and then we can go from there.

Thanks