Some 2008-2009 Taurus, Taurus X, and Sable vehicles built before 8-12-2008 and 2008-2009 Edge, Flex and MKX vehicles may exhibit a harsh driveline clunk at low speed (below 10 mph) during stop and go driving on tip-in (this could be perceived as a harsh 1-2 upshift or 2-1 downshift). This may be due to a PCM calibration.
There is a new calibration that will improve the low speed stop and go driving feel.
Reprogram the PCM to the latest calibration using IDS release 57.10 and higher or 58.1 or higher. Calibration files may be obtained at www.motorcraft.com.
This new calibration was implemented in production on 8-12-2008 for 2009 Flex, Edge and MKS, 10-15-2008 for 2009 Taurus, Taurus X and Sable models.