2001 Dodge Dakota Not the tranny!

In the morning, when I put the truck in reverse or foward, the engine idles high but the truck moves very slow. This goes on for a block or two and then it catches up and is ok the rest of the day, usually. This happened one time when I was going about 65 miles an hour on the highway and it smelled of burnt clutch, though it is an automatic. I ran the truck through the gears on the side of the road and then started out again and it seemed ok. I took it to a Cottman place and they rebuilt the tranny ($2000) but now it is doing the same thing. What's up?