Can still be several things... Likely some part is getting hot and doesn't work until cools.
Example: If trans and/or ground has problems then Motor might have thermal cutoff to save it from mechanical overload, low volts, etc. (Cave, Electric Motors
) I don't have a spare motor to take apart to check for this.
Board or wiper switch w/ hot part(s) can do same.
RD etc "Board Fixes" are mainly a band-aid fix at best.
Get new Dorman board and if needed new motor too.
Check the trans too. Lube 3 ball joints w/ brake grease. That won't wash out or run when hot.
If arm pivots are binding look for another trans. Clean/fix the arm pivot is hard and often doesn't last long.
Iffy Wiper Motor sometime can be save but most people don't have a clue what is their problem. IOW Many try to "rebuild" them following crap on YT et al only to fail again often in the worse weather far from home.
[This message has been edited by theogre (edited 03-19-2020).]