Not sure if this fits, but I had a 60 vette I had just put a new motor in. I was working on something and wound up leaving the key on in run position. After about half an hour, I noticed that the coil was hot. Next day I got the car running, took it out the road and run like a champ. About 2 minutes out, it started running like crap, barely got it home. Looked over a bunch of things, took it for another ride, run like a champ again, almost same exact spot on the road, it started acting up again. Replaced coil, no more problems. So it had a timed/heat issue, that worked fine until that point, and then went down hill fast. But the next time, worked fine again, until.
