I have an 08 Edge AWD with identical problem. "Clunk" happens intermittently after accelaeration from stop. I can feel it in the seat of my pants which leads me to believe that the issue is occurring in the rear differential (AWD). I have had it to the delaership twice. The first time they just reprogrammed the transmission, which did nothing. The second time.......problem can not be duplicated. They are searching bulletins now within the Ford system.