2000 montero jerking..

yea so i was driving my moms montero one day and in about 3rd gear arond 1500 rpms it starts jerking out of nowere its never had any problems before once you go over about 2000-2300 rpms it will stop annd wont do it again till you get back to 3rd and 1500 any ideas what this could be??
thanx in advance, nate

really nobody has anything???

I know it's kinda late, but the transmission fluid does need to be changed periodically, otherwise things like that happen. Get the fluid changed and if that doesn't help get the sensors checked.

Check for codes in both engine and transmission. Check the motor mounts and other supports for wear or oil soaking.