1994 Ford Aerostar Transmission Problems

Hi, about a month ago my Aerostar started losing power going up hills. Then if I would give it more gas it would rev up really fast and then crash back. I thought it was bad gas or a fuel problem (filter, etc.) Last week when exiting the highway the engine did this again and then would not go into any gear. I finally got it to go and then the transmission went out completely.

I had it towed and later my husband checked the fluids, etc and got it the van. He proceeded to drive it (It drove normally for him) for about 40 miles back to our home and then when he went to pull into the driveway the transmission quit again.

Later that night he got into the van again and it drove fine in all gears except overdrive. It was sluggish in overdrive. The transmission fluid smells fine and looks normal. It does not look or smell burnt.

Do we need a new transmission or is this a module or computer problem or what?