Hi

I have a 1986 560SEL that has the following symptoms:

1) Upon start, warm or cold, it runs for a few seconds like it is missing on one or two cylinders, then smooths right out. This is only about one or two seconds (maybe three). But it is rough.
2) At idle (about 900 RPM), warm or cold, it has a very slight surging (perhaps 850 to 950) that is noticable only by ear with the hood open.

I've had the following "professional" opinions thus far:

1) a vacuum leak
2) a dirty fuel filter
3) unadjusted idle "something or other"

All comments are greatly appreciated
Thanks