Might have developed a vacume leak if you're still using vacume hubs. Getting intermitet vacume would cause the motor to hesitate and the hubs to lock and unlock, giving the jerking.
If you have other hubs, check for dirt and corrosion inside, they may need a wd40 soaking to keep locked in place.
Good luck.

2000 KIA Sportage 4x4, Sadly Smushed! Now a 2001 Cheep Jerokee. 3" Rough Country Lift, 255/70/16 General AT2's
http://www.cardomain.com/ride/2292811