420SEL 380SL stalling problem cured!!!!!!
 

Both my 91 420SEL and 85 380SL were having the usual stalling issues. They drove fine but when I was comming to a stop the RPM's would drop below 400 sometimes it recovered and other times it stalled. Hot, cold A/C on or off it didn't seem to matter. I'd say it stalled between 10 and 50 times a week.
One day I went for a ride iin a friends Audi RS 4 wagon (oh my what a car!)When we stopped for fuel he put in the 103 octane and we had a long conversation about fuel quality effecting performance blah,blah,blah. Finally I put in 1/3 a tank of racing fuel mixed with 2/3 91 the car ran great and the stalling all but ceased at the next fill up I put 1/4 tank 100 octane with 3/4 91 occtane. That was 2 months ago since then I have been running 91 occtane and the stalling problem is 99.99 percent gone.
Just my experience

Does anyone have an explanation for this?

No, but i'd check the idle air bypass valve to make sure it's not stuck and is actually working.

thank you.
where would i find this part?

Has anyone else tried this?

I guess the racing fuel mix and octatne 100/103 worked as Fuel injection clearners and cleaned your cars intake, fuel injection etc thus curing your issue. Most probably it was dirty injector and the spray pattern was not even at idle.