87 300e rough idle, oil on/in air filter housing. Why?

[Lui]

Greetings all. I have a 1987 300e with 75,000 miles on it and have noticed that there is oil collecting on and in the air filter housing. It pools around the hose from the valve cover to the air filter, and is pooling around each bolt on the cover.

It also seems that oil is leaking slightly from the oil filler cap, and the area closest to the windshield -- Not sure of the numbering of the cylinders, but if # one is closest to the windshield, then one and two have a little oil around where the wires exit the valve cover.

Prior to noticing this oil collection (took about one month for me to notice it) I would get a mildly rough idle, and very occasionally, the car would almost die when accelerating slowly from my driveway. Thankfully it would not die, and that problem has only happened three times in one month. I also occasionally (about twice a week) get a rough start.

First of all, what causes this leak? Is the rough idle issues related to it considering the chronologic order of events? I would think that oil in the air filter would cause poor induction of air through the filter to the engine thereby providing a rough idle, but a month ago all was clean in the air filter area and top of engine, thus the rough idle started first. Thanks for all responses ahead of time!

Not Really Brief,
Lui

P.S. please forgive my ignorance on this -- also I tried to search for "oil on air filter" to no avail. . . I may have missed something; if so, my apologies.

[Arthur Dalton]

See if any of these breather hoses or the ports they serve are blocked up or crimped..

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=2AO123CS42CA01QCCW&year=1987&make=MB&model=300-E-002&category=B&part=Breather+Hose

[Lui]

Originally Posted by Arthur Dalton

See if any of these breather hoses or the ports they serve are blocked up or crimped..

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=2AO123CS42CA01QCCW&year=1987&make=MB&model=300-E-002&category=B&part=Breather+Hose

Thanks for the reply -- nothing looks kinked for sure, and they don't seem clogged as far as I can tell.

[Lui]

I also noted a dripping sound that seems to be coming from the valve cover area near the windshield. . . .