I've created a sorta "how to" concerning the vacuum controlled factory air flow system that might be helpful as a reference for anyone dealing with issues sometimes encountered. Currently its on FTE as they host photos--in the event my Imgur account went down the images associated with that thread would still be visible. Here's the thread, inside the Full Sized Vans Tech Folder:
https://www.ford-trucks.com/forums/1...-controls.html
Where ever it could be posted here for future reference without going to FTE might serve everyone here well.
TIA