This is a 202.029 chassis car.

The EGR valve is functioning correctly. However, the packing on the valve stem was leaking. Keep in mind that there is vacuum (via the pipe connecting to the manifold) above the valve disc when the valve is shut. There was a fairly significant vacuum leak as a result. After changing out the EGR valve and locating one other small vacuum leak the engine runs very smoothly.

However, too much vibration can still be felt in the seat. My tests indicate the left side motor mount may have collapsed. If you noticed in my first post, the mounts are fairly recent, so I am disappointed to say the least. The original mounts went nine years and 142K and were still decent. These appear to have only lasted 4 1/2 years and 70K.