My 1986 560SL does not have a smooth idle, fell vibration.
It does have 190K+ miles.
It idles around 600rpms.
It accelerates smoothly and powerfully.

I've done the following:
- replaced Spark Plugs
- Spark Plug Wires
- Air Filter
- replaced all 8 Fuel Injectors
- Premium non-Ethanol gasoline
- replaced O2 Sensor with non-OEM part
- installed missing Charcoal Canister
- Smoke Test for Vacuum Leaks - no leaks
- Adjusted Fuel-Air Mixture Screw using my Oscilloscope for 50-50 duty cycle

Have not replaced the Fuel Filter but above idle it runs smoothly.
Could it be a leaky Cold Start Valve?
Would worn Motor Mounts or Engine Shocks cause excessive vibration?
If its the Fuel Distributor, then I'm going to just live with it.

Cruises and accelerates great, just vibration or slightly rough at idle.