Posted for <5zq@cox.net>:

 Hello George,
 
 Welcome to the list. This is a pretty good place to bring up problems such as
you describe. I'm sure that you'll get several replies.
 
 As for our plane, we've never experienced any of the characteristics that you
describe. We've got a small tail LNC2 with an O-320, header tank, standard
wings with fuel to the tips. We've now got over 1,250 hours on 5ZQ including a
lot of left and right crosswind landings.  I often use slips on approach (in
both directions) regularly and have not seen any adverse characteristics from
these maneuvers.
 
 I can't think of what would cause this oscillation. Your theory of rotating
slipstream would seem to be eliminated by the fact that on landing there
should be little or no power being applied to the prop and therefore very
little, if any, "corkscrewing" of the airflow.
 
 Let us know what you discover.
 
 Bill Harrelson
 N5ZQ 320 1,250 hrs
 N6ZQ  IV  11.3021%