1993 Trooper Transmission grinding in 2WD

[scrid]

Hello everyone,
I have an intermittent transmission problem with my 93 Trooper.
When in 2WD mode and I pull it into drive I get a grinding sound coming from the transmission which is most noticeable at about 15mph. I can get the sound to go away if I pull over and shift it into 4WD mode. It's almost like it's trying to partially engage into 4WD when 2WD is selected.
Another possible clue is I noticed this problem briefly last winter when it was really cold. It did it a couple of times and then quit before I could look into it. This winter it is back again and it has been pretty darn cold here. It almost seems as if there a shift solenoid thats too cold to position itself correctly?
I am unfamiliar with this particular transmission / 4WD unit, is this a common problem with this model?
Thanks in advance.
Chris