I tried that test you mentioned, depressing the airflow plate. I don't know if I depressed it too much, but as soon as I pushed it the car stalled out almost immediately and then was hard to resart. Also, when I took the lid off the air filter housing to do this test I noticed there was some oil on the lid and a bid inside the filter around the hole on the bottom where the hose that comes from the valve cover is. It wasn't much oil, a spot about the size of two fingers and not very thick. What do you think this means?
1995 E420 - retired
1986 420SEL - retired