I have a 93 ranger that I just picked up, 2 wheel drive, with the 4 cylinder and automatic. I have a few problems, and wonder how to fix them? When I put it in overdrive, the truck wont move, but in any other gear its fine? when I hit the brakes, the rear tires lock up?

 

update on my problem, I found out the truck will shift into overdrive if im going around 35mph or faster, and I let up on the gas, Is there a switch or something in the trans that is bad?