Have an interesting noise (bang) with my '04. Cruising at 55 with accelerator maintaining 55 MPH speed and then stomping on accelerator produces a "bang" like a broken transmission mount. If I hit 55 and let off the accelerator and then punch it, it is quiet and just takes off. Had the engine and transmission mounts checked and all are tight and fine. I would think it would bang in the second scenario; not the first. Very strange. Any ideas???