One problem related to sway bar has been reported for the 2001 Mercury Sable. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Mercury Sable based on all problems reported for the 2001 Sable.
On Sep 6, 2007, my 2001 Mercury Sable at 56,640 miles was determined to have broken rear springs. My local Ford dealer replaced rear springs, struts, sway bar links, and upper strut mounts. This seems similar to problems that you have previously investigated.