Last night i was driving home, and was going up a hill and needless to say i couldn't make it with all the snow we had, i thought my 95 4runner was in 4wheel drive but it turns out it wasn't. I played with it a little bit and noticed that it doesn't engage it is shift on the go, but even from a dead stop while i was stuck, it would start to pull with the front end, and then at about 2000 rpm's it would just give out, today while i was driving it i tried shifting into 4wheel drive and i could feel the front tires studder trying to go into 4wheel drive. any one have any ideas?

 

I'll bet the Automatic Differential Disconnect (ADD from here on out) vacuum modulator was not engaging the two halves of the axle properly. Its a common problem. Search around here for diagnosis and repairing it.

 

Great thread with multiple solutions:
https://www.yotatech.com/forums/f116...87/index2.html