This problems is very commen. You need to replace the Bushes and the Anti Roll bar links. Both sides have to be replaced. It takes about 1 hour to fit these you have to take the wheels off and put a jack under the car or prefeably on a high lift in a garage. They cost me £30 in total for the parts from a local garage not ford! And the problem was sorted straight away. Hope this helps.
andy webster
November 2006