How do I know my ECM is bad?

it is a process to determine a bad ecm. you need the expierence and knowledge to determine that. a prom is part of the ecm called programmable read only memory. take it to a shop for a diag, stop throwing parts at it and spend your money wisely. Roy

check igition modual located inside ditibutor at bottom two screws and a wire clip to remove. Auto part store will check for free