I went to leave one day truck started just fine then died like 40 sec. Later while I was letting warm up. Its acting like its out of gas but I put a gallon in still won't start

It should be right there before the fuel rail.

Try this:

Turn the ignition switch to ON. When the fuel pump stops running, turn the ignition switch OFF. Repeat this procedure several more times. This will fully pressurize the fuel rail. On the last attempt, turn the ignition switch to START. Keep in mind that you may need to add several more gallons of gas, if the tank was nearly empty.

If the problem persists, consider replacing the Ignition Control Module (ICM). They often cause engines to suddenly die. I recommend replacing them every 120,000 miles or 10 years, whichever comes first. I suspect ICM failure--BWD Part No. CBE28Z, $43.99 Advance Auto Parts, Lifetime Warranty.