I had a dodge van doing the same thing, not shifting up, bought it cheap because previous owner had tried changing the fluid but that didn't fix the problem. I read that the 'pressure sensor' can go bad, they have other names for it too, but I got one at auto zone, it's an aluminum drum like thing about the size of spice shaker, just mounts into the bottom of the trans with pan off, I installed it, fresh fluid and filter and it shifted BEAUTIFULLY, Research this...