Steering wheel jerk

sounds like front A members are shifting from worn bushings, or rear axel tube shifting for and aft, raise up on floor jack and shake tire and wheel for looseness

Yeah, but I'd check the new rack and CV carefully, as I'd guess that you got a bum "new" axle, as they seem to have a 10% or so defect rate. The opposite side doesn't really wear out so much as simply popping open its inner (DOJ) boot, eventually causing grabbing and shake once all the lubricant grease is spun out. Never heard of a bad new rack, but anything goes. Front worn bushings usually cause a shift at higher speeds or in the twisties, but not a cyclic shake that a bad axle provokes.

Did you ever figure out the cause of this. My car is doing the same thing.