Just out of curiosity, this wouldn't happen to be Dave's Small body HEI's would it?
Check the module yourself, It's the only thing that will go thermal on that system..It's not uncommon to get a bad run of them..
Other than that, make sure you didn't mis~wire the Coil + to something like a Fan Relay?? or something going on/off with a temp range..
Try running a direct wire from battery to Coil + and see if it happens again..that'll tell ya if it's thermal or wiring..