When I go from park to drive, my engine jerks pretty hard, and when I shift gears (any gears) I literally feel it. I popped the hood and checked it out and had a friend shift gears. It jumps like 1-3 inches when I shift. Is there something wrong with my engine mounts? Or is it loose and all I have to do is reseat the engine? If I have to replace them, how much does it run?