Vibrating noise coming from under the car at between 1,300 and 1,800 rpm. Noise is a low rumble to a metallic vibration. Like a wind vibration that increases up to drumming your fingers on a dinner plate, but constant frequency. Rpms change (surge?) when noise occurs. Only does it in DRIVE. Does not do it in D3 or stationary in park. More prevalent when going up a slight incline.
**May be related ** if going up a steeper incline, the car will shudder and jerk forward at the 1,300 rpm point.
100,000 miles. Fluids are OK. Tranny fluid looks good. No codes.