When I put the jeep into 4 wheel I have to really mash the gas down to get going and the engine really strains to keep up. It don't matter if it's full or part time, it seems as though it's getting worse. I was kinda thinking the gearing was off " front or rear different" but not real sure that it would drive straight in snow if the rear was pushing or dragging.
This is in snow maybe a few inches, nothing too deep to cause the drag or too little to cause binding.

 

Vicous coupler in the transfer is failing. NEVER use part-time on pavement.

 

stock tires???

 

I don't use four wheel in dry conditions only in snow, also I have 31's on it.

 

There was never a viscous coupling used in 1990. It's either an NP231 Part Time t-case or an NP242 Full Time t-case.

 

Are the front tires worn evenly? Even the slightest difference in diameter will cause binding, but that is in with a traditional Tcase, odd it does it in Ftime.

 

I keep the tires rotated so I'm out of ideas