I had a 70's mopar with stock electronic ignition. When warmed up and running, all was ok. But, if I stopped to run into a store or other quick errand, the engine would not start when I returned until it had cooled down for a half hour or so. It would then start and run fine until the next time I shut off the engine again. I was able to diagnose that the reluctor coil was the culprit as it would "heat soak" and the coil would "open" until it would cool. A new reluctor took care of the issue for me.