[Canucklehead]

First thing I would do is get my receipts/work orders for your previous trips to the dealer which didn't result in fixing the problem. I would talk to the service manager and show him that you have been trying to get this problem fixed since before your warranty expired and tell him that you do not expect this to be handled as if your vehicle is not out of warranty. If he tries to tell you that there isn't anything he can do about it inform him that you will be calling Isuzu Customer Service to discuss the dealer's warranty policy regarding this issue as well as the Better Business Bureau.

Now regarding your 4WD problem, does it occur when you are driving straight or turning? Does it occur on dry pavement or when the road is snowy/slippery? Are all of your tires the same size?