On occasion (at speeds of 40mph and up) the front end of my 1987 300D will vibrate. I can feel the vibration in the steering wheel. Sometimes if I brake or change lines, the vibration goes away. Other times it goes away by itself. It's only for 10-15 seconds at a time, but is getting quite annoying. A couple weeks ago there was NONE of this, last week it was rare, and now I'm getting it almost every time I drive the car.

The steering damper is new, the ball joints and tie rods look good, (no rubber is torn).