transmission troubles?
 

Good morning my name is jim i am new to this forum having recently purchased an 1997 mountaineer awd. I have been a ford mechanic from 1990 till 1996 so if i can help anyone here i will try. i am no good at tranny issues though so if anyone can help me with this issue it would be great. my problem is as my truck is on a incline in park it wil roll back at a rate of about 12 inches every ten minutes. fluid is full in tranny just yesterday it started slipping on take off and when passing a car but other gears are working fine. not sure if related i beleve the transfer case is a hydrolic run one correct. so maybe that, any help would be great. even if you dont know answer can some one at least reply they dont know so i know i did this correctly. thank you jim