I have a 2002 Dodge Ram 1500 two wheel drive with a 4.7 liter engine.
It's been overheating so I replaced the whole cooling system:
The only other thing I think it could be is the computer.
I believe that fan has a two speed motor, three leads on it. One is low speed operation which is turned on by the AC system. The second is the warm engine connection which is high speed fan. This is controlled via a temperature switch through a relay.
With this knowledge need to test and or replaced the temperature sensor and the relay that is this high speed part of the fan. Or if you have a volt meter then measure the fan connection for this high speed circuit looking for it to turn on and off with rising heat.
The circuit is pretty much the temp sensor, relay, fuse, and fan (plus wiring).
It is not an answer exactly but I can't comment yet...sorry for that...
It might sound weird but sometimes wrong cam timing can cause overheating of a motor because the combustion is not as efficient as it should. A lot of the heat is trapped inside the chamber and not exiting the cylinder properly. Since you replace the whole cooling system that is the most logical explanation.
Finally make sure that nothing is blocking the airflow to the radiator. The most obvious is in front of the bumper but don't forget the section between the bumper and the radiator.
Try burping the system. My 02 dodge did same thing and I replaced water pump, thermostat, fan clutch, radiator, and even flush the system. Some reason heater core sits higher than reservoir so you have to Jack front end up on ramps and then burp the system. Once I did this no more running hot.
When the vehicle is cold pull the radiator cap off making sure that the radiator is full of antifreeze start the vehicle up now if you see bubbles coming up from the antifreeze almost at a regular pace it may be a blown head gasket
