GMC Repair: chevy pickup 3500 silverado 7.4l, chevy pickup, faulty sensor

Question
I have an issue with the truck when it comes to starting. What would cause NO Spark and NO fuel. Some times it starts and runs fine and others not. When the issue arises both spark and fuel stop! The Truck turns over every time as long as the battery can hold out. The check engine light has not appeared and today i drove the truck for 2 hours with no issues.

what wires tell the engine to not start?
Could it be a faulty sensor killing the engine?
Is there a wire that is being ground out i should look for?
Could it be a fuel pump issue?
Could it be a default shut off if i continuously hear the fuel pump when the key is on the on position?
Should i follow a wiring diagram, does anyone have one?
could it be ECM?
Please help.

Answer
i would try lightly tapping on the ECM as the truck is running, if it falters at all or stops running then it is in fact an internal failure in the ECM.  Otherwise you are going to need a scan tool to see the sensor parameters when the truck is in the failed state