I have an 05 Navigator. I had some rough idle issues, like on one red light engine would idle a little rough (RPM is fine though) and after few miles of driving on another red light engine would idle just fine. So I thought cleaning MAF sensor might help solve the issue. Long story short; I pulled the sensor out and noticed it had some oil around it. I've uploaded a video on YouTube showing where the oil is. Also, I've taken some pictures of the filter. I also noticed a oil-like stain on the polyester part of the filter.
Did anyone had a similar issue before? I have no idea why/how oil might reach that height. My initial thought was faulty PCV sensor, but AFAIK this engine does not have one (it's different than 03-04's, which has the PCV hose on the passenger side of the engine).