A little more description would be helpful. Do you mean when you put the lever into one of the 4x4 modes, it just clunks & jerks?
The chain in the xfer case could be stretched (allowing the chain to slip on the sprockets). If you've got full time 4x4, could be you just need an oil change in the xfer case.
Yeah it's all wheel drive quadra drive we jacked up the jeep and front drive shaft turned as fast as the rear did so we took the cover off the front upon further inspection looks like someone might have put wrong drive shaft in driver side shaft didn't even go all the way into the hog head so bought the longer one waiting on my buddy to get back off the road to assemble it back together see what happens I just bought it a few weeks ago and I personally don't know much about them so have to wait on him lol hope it works
This happened to several already. For this reason it is always a good idea to compare the old and the new part with each other, to be sure that they are exactly the same. Most probably your problem will be solved with the right size axle shaft.