I have a 1987 560 sel.It ran great from 1500rpm on up but at idle the whole car would shake.Sounded like a vacuum leak.But what it was was the Lambda(?). I noticed the tower in front of the fuel distibutor had the cover off so some one was messing with it.Anyway I just started adjusting it clockwise(richer) until I got it pretty good.Total of about 3/4 of a turn. It also solved my economy guage problem.At idle it used to be about 1/4 of an inch towards the right in gear, now it is almost full left.Also my erratic shifting is gone nice and smooth. It is not perfect but it is about 80%. I am going to adjust the EHA when I find a 2mm hex. I will see what 1/4 turn does.
It is like a new car!