Truck shuts off after engine is warm!

It usually takes around 30-60 seconds for the engine to go into closed loop n the O2 sensors take over the job of regulating fuel flow to the injectors. The engine runs in a default mixture until then. Dijya replace ur O2 sensors when you replaced the engine. Try unplugging the upstream O2 n see if the engine will run then. BTW, the popping noise you describe can be caused by not enough fuel to sustain proper combustion. Fer sure fix???...no, but a good place to start.

I haven't replaced the 02 sensors, I'll give that a try. Thanks Jet I'll let you know what happens.

Messed with 02 sensors, didn't do nothing. Started to wiggle around on crank shaft sensor, started truck ran longer this time about 20 mins! Then....shut off..

If that's the case, then maybe the sensor is loose in it's mount or you've got a bad connector/wire to the crank sensor or the sensor itself is bad. Make sure you replace it with a mopar one n not aftermarket. They're notorious for not liking aftermarket crank sensors.