1991 Ford Bronco No Power - Stuck in 3rd Gear?

91 Bronco with 5.8L, automatic trans.

This morning when I put it in Drive and stepped on the gas the truck barely moved. The engine was reving at about 2000 rpm, but the truck was just creeping. It felt like it was in 3rd gear. Reverse works fine. I dropped it to 1st gear and 2nd gear and it moves better but I can still the lack of power.

Even after I slowly get it up to 50-55 on the highway, there is no power when I give it more gas. If give it too much it bogs down and starts to sputter. A slight incline on the highway and I slowly lose speed because I cannot give it gas to accelerate.

This happened once before, but working it back and forth in the street seemed to eventually fix it. I drove it 10 miles this morning and it was still doing it.

Appreciate any advice.

Brian