well i got a little problem i start to drive in my car and change gears to second and get aroung 15 to 20 MPH and cruse for a few seconds and then excelerate to to about 25 then let go of the gas pedel and hear a knocing sound just once and it will do this every time it dose this with out fail. i think it could be my two lower moter mounts but i have been told different any help will do