A friend of mine said the shimmy in his steering is caused by a bad filter in the power steering?
Ever hear of this sounds like another experimental waste of money.
Easy to tell if it is that. Open the hood with it running and turn the wheels all the way in one direction. Then raise RPM a little and see if the pump is pulsating real bad.
P/S pump filter in my M2 is easy to get to, just open up the filler cap and there it is, small and cheap. I replace mine about every 250,000. The first time I discovered it, it had unscrewed itself.