Wiper motor issues

I'm not sure if some of you seen my post in another thread (wasn't trying to thread jack) but if you haven't, here is the issue.

My wipers worked fine until a few days ago when I was warming up the Valiant. I turned the wipers on as there was some water droplets on the windshield that annoyed me. I decided to check out the "high" setting, something I have never done in the 3 years I have owned the car. They hesitated, then died.

Ok, yesterday I went to my brothers because he has all the wonderful tools lol. We found out that the motor is getting power from the switch. So, obviously it's the wiper motor. Well, after trying different things hoping to get lucky (like cleaning the brushes), my brother decides to make sure it was getting proper ground. Bingo, that seemed to be the problem....sort of. We ran a wire from the battery to the wiper motor and it worked, but very slowly. Actually, it would run very slowly and stop until you pushed the wiper to get it to go again.

So, we both decided that since we don't have the wiring schematic handy we shouldn't continue until we do so we know which wire is ground.

Well, here's the thing though. I still have the "ground" wire we installed hooked up and the wipers worked perfect when I got back home. Went out to check them again 30 minutes later and they didn't work at all. Then about an hour later they worked just fine again.

Any ideas what is going on here? It's obviously a ground issue, but why are they acting all crazy with a permanent ground from the battery?

Edit: Sorry, when it comes to electrical issues I am clueless.