Well, going from exfat to fat 32 seems to have helped some. It still has some drop out, but not like before. I'd say it's probably reduced to 1/2 or 1/4 of what I was experiencing.
I haven't used any in a while so I don't remember specifically the app names.
If you search the Play Store for SD cache I see some but some of the hits are for other things related to cache, so you'll just have to judge by their names.