Is it my ECM?

RSF2001Ram

My 2001 Dodge Ram 2500 w/ 5.9l will arbitrarily shut off on its own. The Speedometer will read, if I am moving. The tachometer reads 0. The other gauges will freeze until I cycle the key, then they drop to their "Off" position. When I cycle the key to the "RUN" position, they will move slightly, but not read. The odometer window will read "No Bus". The idiot lights will cycle if I turn the key to the "RUN" position. When I attempt to start the engine, the starter turns the engine, but it is as if there is no ignition being sent. I believe that the ECM is overheating and shutting itself off until cooled down. It happens most often when I am Idling or doing city street driving. It has happened on the freeway, but seldom.
I can have the key in the "RUN" position, and when "it is cooled down" the gauges will read correctly without recycling the key, and it will start.
I have found the when I pour water over the ECM the time it is "DOWN" for shortens over times that I do not.

PF_Flyer

If the ECM it self is having an issue, shouldn't there be codes stored in it that would indicate what the issue is? OR, it might be that there's an electrical system that's causing the overheating like a bad voltage being supplied to the ECM. I think I'd start with looking at the ECM.