Truck stalls when going from 2nd to 3rd gear

latemodelracer

Went to drive my '05 Colorado today and something weird happened. As I was driving along, when the auto trans was shifting from 2nd gear into 3rd gear the RPMs dropped and the truck seemed like it wanted to stall out. Pulled off the side of the road and waited a moment...did same thing again so I turned around and took the truck back home. The truck had been running around 10 minutes so it was somewhat warmed up when this happened.

Any insight would be greatly appreciated!