4X4 problems need help!

I have a 01 4X4 tacoma single cab 2.7L with a 6" fabtech lift and 35" tires I have had it for over 2 years now and the four wheel drive has worked perfect but now when you put it in four wheel drive it goes in indicater light comes on and it is fine till it gets a strain on it like going up a hill or going thru deep snow or mud then its like it doesnt totally engage the way it sounds is like the front wheels are coming unlocked and they bang in and out of fourwheel drive the rear wheels always spin but the front its like it slips in and out then when i go to disengage it from 4X4 the light goes off and only rear wheels spin till i start going down the road then it like slams into 4X4 like its not completly disengaged any info would be a huge help here thanks so much i am not fimiliar with auto locking hubs or half shafts all my other trucks have been straight axles

 

Bumping this from years ago. I think I have a similar issue although not nearly as extreme. It's just that when I leave it in 4x4 and then start it up again, it feels like it is "slipping" until I get to maybe 5/10 mph then it fully engages and rides fine. If I put it back in 2wd and then back to 4x4 the problem is solved. Did you fix your problem? Anybody out there have advice? Thank you.

 

Starting to think that perhaps this is just from turning too tightly to get out of my parking spot. Could the answer be so simple?