I think your problem lies in the blower motor resistor. I know you have changed it for a cheap one but I have gotten bad ones out of the box before. I have looked over the schematics on page 24-60 in the service manual and you have changed everything else but the motor and the wiring itself.
https://www.crossfireforum.org/forum...-resistor.html
This was an amazing write up that you turned into a PDF about 8 years ago it has the wire color and everything and the voltage you should have at them.
Good luck and keep us posted.