I just bought a 99 1/2T it has a new water pump thermostatrebuilt radiator and cat. and still runs 210 or warmer could the thermostat be in upside down if so would it cause it to run warm.It also gets bad fuel milage and has no power.

 

Either you could have air in you cooling system, may have to be bleed. Bad thermostat or a blown head gasket

 

210 is acceptable, over 225=bad juju. A backwards T-stat would definitely cause overheating well beyond just "running warm". Make sure the system is purged of air (fill, let it get to OT, then allow to cool down and check level again). Make sure you're not loosing coolant; The magnums have a bad habit of puking where the timing cover meets the block, and that part of the engine stays hot enough to bake the coolant before is ever hits the ground, unless the leak is severe.

 

you might just need a new clutch fan