Yesterday my daily beater took a dive. Cant for the life of god figure this one out.

96 blazer while driving to work the truck would want to stall out and die. Gauges started going up and down. Pulled off the road gave it some gas and it would idle fine. Got it to work and turned off the truck. I went out for lunch it drive fine. Tried to go home and nothing. Car would crank but not start. I ran a ecm scan to see if any error codes ( i carry mine on me) and only one normal code I always get P0420. I cleared the code and rechecked it and no new codes. Ran to the store bought a new iginiton control module. I replaced it and that didnt help. Now I cant read the dam ECM and I get no dash lights or dash activity when I turn the Key. I get no ECM reading from the tester. It errors out when trying to read the ECM. Car cranks but wont start.

New battery, alternator tests good as so does the starter. No blown fuses at all. I took off the master electrical connector above the brake booster and cleaned out just incase. Truck still wont start. Cap, rotor wires are not even a year old. I got proper fuel pressure. I am stumped here. I hope my ECM isnt fried. Appreciate and help.

Thanks