Had kind of a similar issue, hot sure if your car shuts down after running for a bit or nor. What happened with mine was changed my ECU box to a mint looking one because I can, LOL. So with this different mint looking ECU I was letting the car idle and warm up and it just stopped running?? so I went to restart it and it wouldn't start right away, after a while of sitting it restarted fine but quit again after a while, turned out that once the ECU box warmed up it just shut itself down till it cooled off, Not sure if this helps you out or not but if you have a known good ECU try that??