At somewhere around 50,000 miles, my Edge suddenly has excessive noise from the engine. It is most severe around 2200 RPM, and increases while working harder, such as climbing a hill. There is a "HUM" at that engine speed, which seems to be where something is resonating, but at all speeds, there is a very mechanical-sounding noise whenever the engine is working harder, such as accelerating from a stop. Engine performance seems normal, and transmission behaves OK. I have looked at exhaust mounts, and as much as I can at engine and transmission mounts, but can't see anything obvious. Anyone have any suggestions? I could create and post a recording if that might help...