Decided to change thermostat, no real improvement. So, here's my latest thoughts / observations, would appreciate some comments:
When I pulled the old Blend Door unit out, there was a plastic piece that fell off onto the floor of the van as I removed the Blend Door assembly, it resembled a gear cog of sorts. I examined it, it did not appear to be broken or damaged, it looked like it slid onto the shaft that protruded from the back of the blend door assembly. This part is obviously crucial to proper operation. My initial fear was that upon reassembly I was not sure which way this gear cog was supposed to fit, but as it turned out, it could only fit one way.
I also noticed that the shaft protruding from the back of the old Blend door unit was at one clock position, most likely where it decided to fail, while the shaft on the new unit was at a different clock position, most likely the factory default position. I tried to move the shaft on the new motor so its clock position would approximate the old one, but it wouldn't budge, so I decided to put the gear cog on the shaft the only way it would fit, then I installed the new Blend Door Unit, I figured the calibration process would take care of the clock position.
So, if the gear cog was installed at an incorrect clock position as I described, is it possibly it is so far off that the calibration process could not realign it? As I mentioned, when I run the calibration process, it terminates without errors.
Also, here is more information and another symptom: There are 5 (front facing) vents on the dash. The drivers side slider controls the air temperature from 3 of those, the 2 in the middle, and 1 that is far left. When I move the driver side slider to HOT, the 1 on the far left stays relatively cool (although not COLD), while the 1 in the middle that is closest to the passenger side actually gets warm (but not HOT like the air coming from the passengers vents when I move the passenger slider to HOT). This happens whether or not the passenger slider is on COLD or HOT, kind of strange, but maybe another clue?