Take the temp with a temp gun. If you don't have one, do the waer test on the head. Boils off right away = too hot. Sits there = too cold. Sits thee for 3 secs and them boils off, you're in the general ball park.
If it was overheating, the head has a "burnt paint" smell. It will also be very hard to start till it cools down.
When the truck takes off what is it doing? Reving high then moving? Or just being a slug in general. It can be either it's too rich, your clutch is bad or your slipper might be too loose.