The jerking and pulsing is because your front wheels aren't sliding.

When driving in 4wd you need to be on a soft surface that will allow the front wheels to slide a little in turns because 4x4 means all 4 wheels turn the same. So, when your TRUCK turns your front wheels need to make up / compensate for the distance they are traveling since they turn in rotation with the rear. To do this, they slide.

You also should not be using 4wd on pavement. Unless their is snow on the ground or a shitload of water.