Am I Overheating the Tranny or killing the Torque Converter??

I just got back from slinging a little mud out at our school's ski hill but my trip was cut short because I started having what I assume is some sort of tranny problem. I have a 91 w/ the 4.0L, the AW4 (172,000 miles), and the NP231. and after climbing up the hill in the mud spinning pretty much the whole way I came back down and found that it wasn't running right. It was reving to 1500+ before it was really starting to move and when I tried to get up a headlight high hump I just sat there with the engine reving and the tires not turning. At that point I left to get back here and the whole way back it was reving high off the line and when it got up around 4th it seemed like it was almost not going in and it was running 2200ish at 55mph where as it is normally closer to 1800. When I shift into reverse though it acts normal and backs right up at a reasonable rpm. I checked the tranny fluid when I got back and it is full and it is a normal shade of red without any shiny particles in it. Could I have just overheated the fluid, or could this be something more serious like the torque converter? Any thoughts would be greatly appreciated.