Well in my 02 it takes a while especially when it take about 5 to 10 to warm the engine I do have a 4.7 though. There is a pump that pumps antifreeze to the back you could see if it is going out it is located near the right passenger fenderwell.
First, my apologies to dustinb for highjacking this thread.
I believe the pump is gone on my D. I can't seem to find a replacement part at any of the usual parts places. Is this a dealer only item? Anyone have a part number or reference for this thing?