Yeah, I agree with the coolant temp going up slightly while wheeling; enough to bring the idle back down to normal. To go along with the this if I shut the truck off and start it back up 5 minutes or longer it will idle normal (acutally lower than normal since the idle screw is in the entire way - again, this is because the coolant is slightly warmer now since it's not being cooled).

The thermostat was replaced with a 190 degree toyota stat; I don't think that's causing the issue.

93' Toy xCab
bobbed > 22rEB > w56 > stock duals > SAS > 4.88's > 37's