I picked up a 2002 dodge ram 1500 4.7 to use as a plow truck but it has no heat. This is what I have done so far I have flushed the system replaced the heater core (old one was leaking) checked all the blend doors while I had the heater box out. I also replaced the thermostat twice. I have tried running the truck with the radiator cap off and the front end elevated. I get a very little heat from the vents. I have also noted that when I rev the motor up to 5,000 rpm the temp gauge goes from the middle to the cold end. I get a little heat at that point. When I leave the car overnight the next day when I start it up no heat again no matter how long I run it. I also noticed that the lower radiator hose stays cooler than the upper hose. Do I have a clogged radiator what else could it be water pump maybe. I am tired of tossing parts at this thing I would like some direction from here.

Cars & Trucks - Dodge - Ram Pickup 1500 - 2002 Dodge Ram Pickup 1500