Welcome to Just Answers, I'm Kevin and I'm here to help resolve your Automotive issue Please click the ACCEPT button when satisfied with your answer. Hello and thanks for requesting me. I suspect you may be experiencing 4WD bind from your transfer case section of your transmission. Refresh my memory, is your Subbie a stick or automatic?
If it's an Automatic, the issue is in the clutch packs of the transfer case(center diff) the common repair involves removing the back section of the transmission that contains the transfer clutch assy and inspect and usually replace the clutch pack and sometimes the housing and transfer solenoid, this repair can cost in the area of $1100.00 to $1300.00 dollars.
Now with that being said, I have had about 80% luck with first performing a complete transmission flush, with our Wynns flush machine and then (very important) adding the Wynns "Shudder Guard" additive after the flush. after driving the car between 50 and 100 miles after this service , the shudder, studder or wheel hop, disappears. This fix is based on the service reconditioning the clutch packs, if you have a more serious problem , more on hands repair would be needed. The Flush service usually runs under $200.00 and is a good gamble for this issue. Just find a shop or dealer that offers the Wynns Trans flush system.