The XJS and the pre-88 XJ6 have a problem with rack bushing degradation. These bushings hold the steering rack in place and absorb some of the road vibration. Unfortunately, they tend to decay and fall apart given their usually hot and oily environment. The permanent solution is a set of Polyurethane or Neoprene rack bushings. These restore the sporty steering your Jag is supposed to have, and they never degrade. We sell them on the website under part number CAC1635K
See our Jaguar Parts Store Catalog to order parts.