Did you make sure that the ECU is grounded to good clean metal and not screwed down to painted metal.
Check your oil pressure with a good mechanical gauge.
Yes a misfiring engine can run hot.
You said you fired it up again in one of your later posts - How did it run?
What are you running for rocker arms? If adjustable how did you adjust them? Just a thought but if adjustable they could be adjusted too tight and when the lifter pumps up they are holding the valves open.