I parted out a 92 dodge diesel about a year ago and the whole drivers floor was rotted out so they siliconed an old warning sign to the floor, it was warning you that alarms would go off if you entered the property
Replace the Coolant Temp. Sensor right away. The $8 one on the front of the motor next to water neck.
Unhook it first and see if it runs better. This is most likely the problem due to the symptoms you're describing.
I believe there's a thread exactly like this full of pics on 67-72chevytrucks.com in the 73+ forum. You should see some of the scary **** in there. http://67-72chevytrucks.com/vboard/showthread.php?t=218695&highlight=Previous+owner+fixes
this was on the 81 C10, this guy was a complete HACK...
most dangerous tool in the garage
JUST KIDDING, that thing is actually safe and fun. usually a combo not together....
This is actually the most dangerous tool in the garage. i call it the porcupine...it'll turn you into one