Eagle Talon 95 ESI: Power to ECM ECU PCM questions?

The ECM is basically shutting down while driving and then no CEL, no start. Later starts after 5-10 minutes and sometimes tapping it makes it come back online. OBDII has no comms and only error during this "mode" of shut down.

I'm having trouble finding answers to this problem and everyone I talk to just scratches their heads. People who should know a lot more than me about cars seem dumbfounded when it comes to the ECM. I guess that's why most shops tell people to replace the ECM even if they have no clue.

Questions..

What can cause an ECM to shut off besides a short or harness?

What is the clicking noise the ECM seems to make before car shuts off as well as the ECM?

What is the best way to test the power and grounds if the problem is intermittent?

I can't find any fuse or relay for the ECM or it's memory. When it shuts down like this it resets any trouble codes it had but the only one it gives is rear O2 sensor which is disconnected. But why would the ECM erase codes regardless?

It's not the ASD relay because I've tested hooked up and bypassed. The ECM is shutting off, no CEL with key to ON until it wants to start then you see CEL and will start.

All of the fuses I see are large fusable links and none ever fry. The smaller 12v relays are for horn, fan, a/c, etc. Shouldn't there be a fuse to protect the ECM?

Any help would be appreciated.