dang that is wierd, I would check the normal...fluid, tranny/converter bolts. But it sounds like fluid problems...ie not getting any!!!! plugged filter or pump failing
I would put a pressure gauge on it and see what the heck is the problem. I had a car once that would suck up the plugged filter screen and freewheel then I shut it off and the screen would fall back down and I could go, for a few more feet and plug....
ed