This could also be the new suspension settling in. My friend's Jetta was haywire for the first half of the day after lowering it. If you haven't already, get it aligned. My car doesn't jerk anywhere. What kind of springs/struts did you get?

99 SVTC, T-Red, #652/2760-12.8.1998 Mother#@%@!* did I sound abstract? I hope it sounded more confusin than that!