Oil everywhere

[moemo]

I went to replace my air filter, and I found oil in the housing all the way back to the air chamber?????1999 windstar 3.8 125,000 miles

[wiswind]

This can happen from the PCV line.....a small amount of oil is not unusual.
The PCV system will pull a small amound of oil vapor from the crankcase.
The location of the PCV line entering the upper intake manifold will permit some oil vapor to go back out the throttle body once the engine is shut down.
However your year has some issues with the PCV oil......dealing with the front valve cover and the isolators on the bolts that hold the upper intake manifold down.

First thing to look into is the information in this link.
http://leckemby.net/windstar/windstar01.html

This link has information about a modified front valve cover.....they modified the baffel at the PCV valve location to reduce oil being drawn up.

It is a very good idea to do the modifications listed in the link.....and it will prevent problems in the future.