i had the same and found out it was a shock absorber,, ford wont do it under warrenty as they only covered for 1 year, so i got second hand one off e-bay because putting new on would meen doing both sides, easy do, but b4 u do it get car up in the air so shocks are fully extended and have a look if there is any leeking on them, mine was covered in oil, common the seals go on them