Something we do in racing to build trans heat is to load up the torque convertor. Of course, we have transbrakes to do it with. I've had a little luck doing it in the dakota, but the low stall doesn't let it build much heat.

 

It warmed up.. and it works again.
Apparently, it's a common issue. A buddy of mine with 2010 F150 had the same problem during this cold wave.
Thanks for tips everybody!

 

Glad to hear it's working again! I wish mine was that easy............It was in the high 20s F and it's still NOT shifting