Dodge Dakota 3.9 manual OVERHEATING

coolant temperature sensor?? it wouldn't hurt to change your coolant either. older coolant creates a static charge that could easily interfere with the many sensors in a vehicle. pain in neck sure. good luck

Along with everything Randy said, make sure you bleed/burp the air out of the cooling system.

What brotherben said. I stress this so much, ALWAYS burp your system after major repairs such as your radiator and pump. Air causes absolute havoc in the cooling system. Good indication is itll heat up super fast while idle but will most times even itself out while.in motion. Bleed that system. Might even have to do it twice