So, when i put my tacoma in 4wd and go over 10mph the car will lunge to the left and right and pull really badly. Any ideas? I'm guessing a speed sensor, but know nothing about it. Bought the car used. I guess the gears could be mismatched too. Thanks!

 

if the gears were mismatched.. you would have dropped your driveline the 1st shift... so its not that.. sounds like something is bent..

 

What could possibly be bent that would make it pull to one side all of a sudden?

 

If your gears are mismatched, it will do this. It won't necessarily drop your drive line. I accidentally did it in the snow and my truck pulled, but no damage (and I did check everything out).