Truck stalls out when decelerating

Good afternoon,

I would check the fuel pressure during the time it will not start to see if the fuel pump is working.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Fuel Pressure Specifications:

Engine running or key on .................... 64 +/- 8 psi

Engine off .................... 64 +/- 8 psi

I would also check for spark as well. Make sure it has spark while cranking.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

If you have any starter fluid, try spraying it into the air filter and see if it starts and stalls.

Roy