My 2002
Dodge RAM is overheating. I have changed out the thermostat and verified the water pump working. The hoses into and out of the radoator run warm to hot after awhile. In idle, the truck slowly heats up but does not really overheat until I drive down the road. The heater and defrost only blow warm air when idle and then cool air once we are headed down the road and the A/C blows moist humid air instead of cold air. I have not tried to replace the radiator cap yet but I am open to all suggestions.

Sounds like a corrosion or phosphate scale problem. You may need to flush the system and replace the radiator. Refill with a 50/50 mixture of G-05 and distilled water. The link below may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235973

It sounds like the heater core needs to be replaced. My hubby truck had the same problem but we were lucky it was just the Rad Jug