02 Mountaineer tires squeal on tight corners

2002 Mountaineer 4.6L AWD 114K miles.

Tires squeal chirp and break traction on tight corners. Appears that AWD is locked in and not allowing any "give" on dry pavement.

No codes, no service messages.

Any idea on a fix?

Borg-Warner 4410 transfer case (model without RSC stabilitrac, no motor on case) has a viscous coupler like the jeeps that freezes up, causing in effect 4x4 lock.

I was told by tranny rebuilder that Ford has a TSB on the transfer cases (with RSC) that would cause a disengagement problem.