Poltergeist in my electrical system

I have a 1995 Mercury Village minivan that has a Nissan engine. It still looks and runs good. However, I seem to have been invaded by a poltergeist in my electrical system. Sometimes the dashboard lights suddenly go off. Sometimes the windshield wipers quit. Sometimes the ac suddenly starts blowing hot air. I’ve taken it to two different mechanics who both thought they had it repaired. But after a week or two, the nasty business started again. I could live without the dash lights, but in Arkansas, it’s just not possible to go without windshield wipers. Sure could use some advice.

I guess I should clarify that the next time I start my van, whatever had quit working before starts working again. And I meant to say Mercury Villager.