Its funny you mentioned that hydra. I was thinking of doing something like that. My garden hose is frozen so I've been trying to think of another way.

 

I know someone that had a similar problem with her '99 D. It happend to be only low level coolant. Maybe just give it a second look since you did all that work with the water pump.

 

OK I want to take a stab at this! Norman does your D have rear cabin heat/ac? The reason I ask is when you replaced pump I assume you drained coolant and you may not have put enough coolant back in allowing for rear heat/ac system. Getting more heat at above idle sounds like your coolant is not up to capacity and as you increase rpm the pump will increase pump pressure/flow enough for coolant to raise temp by more flow but not while at idle. Anyone correct me if I am off track on this. If in deed you do not have rear heat/ac you may have air in system. Just a thought!

 

Get a pump for a drill and a 5 gallon bucket. You can use hot water from the bucket then.

 

Well I did like hydra said. Alot of junk came out. Now the heater works great. No Augie I don't have rear heat. I wish I didn't. There is some day I'm burning up and the kids are still cold.