[tblake]

Are they Napa rack and pinions? I went through a few of them (under warrenty) for the same issue you are having. I finally sdaid screw it, I cant keep changing these darn rack and pinions all the time and I went and bought a "used" stock one from a boneyard with 50k on it that comes with a lifetime replacement warrenty. So far so good. Not to mention the valving in the Napa replacement ones must have been junk because the stock replacement steers so much nicer.

But to answer your question, check for binding ball joints, strut mounts, or struts. WHen you have the rack out, tie rods disconnected, and the front end of the car jacked up, turn each knuckle by hand and see if both move fairly easy. If one or both turn very hard, something is hanging up.