Had an engine swap recently and the new donor motor (a 1983 Euro 300D NA w/ 161K miles) is far better than the old one. Car drives like a dream. Great acceleration. Great compression and burns no oil. Had new motor mounts installed. My concern is the car shakes/rocks while in gear at a stop sign. Worse in DRIVE but still shakes in NEUTRAL and PARK. This is far beyond seeing the motor shake under the hood. The car rocks so bad I see the outside mirrors shake. I had two Mercedes shop owners look at it yesterday and both realized that the M-IP has no idle adjustment screw (which I already knew). One owner said the shakes are due to a harmonic imbalance between the IP pulses and the engine. Think of sound canceling headphones where a sound wave of the exact opposite amplitude will cancel the sound but the two pulses are such that the vibration is amplified causing the shakes. What can I do to smooth things out? I've already done a Diesel Purge with two cans with zero shake lessening. I was told to drive with the high idle cable set just high enough to stop the shakes but IMO this is a band-aid fix. Will adjusting the fuel delivery screw or increasing the timing (it's set to normal) smooth things out? If not what are my options? The car is so close to running perfect that I'm determined to get it perfect.