I am NOT an auto-electrician. I didn't even stay in a Holiday Inn Express last night, so take my thoughts with that in mind. I always start trouble-shooting the low hanging fruit. If I pick it and the problem is resolved, then all's good.
I've had something similar occur after a torrential rain with significant humidity for some period of time and cleaning the battery terminals and posts seemed to have solved the intermittent issues I was experiencing that were similar to what you've described.
I have no logical reason that worked other than perhaps the battery terminals were just corroded enough that the extra moisture involved sent them over the edge, resistance-wise, and they were fine after they dried out. I really don't know enough to postulate any further. But cleaning the terminals and battery posts took care of my issues.
If that works for you, then I'm a genius and you can congratulate me. If, OTOH, you clean the posts and terminals and it makes no difference, then just pretend I never posted.