Check to make sure the regulator is tight to the door and that all of the other adjustment screws are tight. If its continually jumping, it sounds like you have a loose screw or rivet. If you use bolts to screw in to the window motor, they require thread locker to stay in for the long haul.
While you are in the door, it probably makes sense to lubricate.Sil-Glyde will match up to the grease already in there and help smooth things out. The only place I can find it in my area is NAPA.