There's no way it's electrical.
Boy, sometimes it sure would be fun to travel around the US just chking out problems with these cars.
I wish I could help you more, but driving, then not, then driving again is a real odd thing. (Very rare)
I would have to say at this point, that it's going to have to come out for internal inspection.
I still suspect it may be a highly worn clutch pack.
OOOrrr, it's possible the main valve in the pump is sticking when it warms up. ????
Anyone else have a thought about that?
.......this might be dumb and I know its all mechanical but do you think some kind of wiring problem coul be a cause.....after te engine rebuild my gas gauge has been on E all the damn time! It was fine before