HELP ..Runs dies No start .. then start

Don't feel like the lone ranger. Aftermarket ecu's are giving me a fit right now. I'm having the exact same problem. A decades old 5 pin will start the car and run it fine, but any new ECU, I've tried 4, and it won't start or run. I've got a GM module setup I'm eventually going to put in but the troubleshooter in me wants to fiddle with this until I figure it out. Next two things I'm going to try, is swapping the distributor wires to see if the new ecu's have pins 4 and 5 swapped (or the two distributors I've tried with same results) and then a new ECU connector to make sure I have good solid connections. I'll be watching.