OK, so I just took a look at my Vararam and the MAF sensor (I love Monday's off work!)
Surprisingly, I also found oil residue in my vararam, and the MAF sensor, while I wouldn't say caked with residue, was far from being clean. See the picture below.
Off I go to my local parts place for some Cnc MAF cleaner. Hit the MAF with the cleaner back and forth 15 - 20 times. Cleaned out the vararam as well. Let dry and re-install. Haven't driven the car yet to see if this makes any difference for me, but now I know to check the MAF more often.
What's strange, is that I have never re-oiled the vararam filter, as I only have maybe 5,000 - 7,000 miles on it, and the car only goes out on nice dry days. I can't say for sure, but the oil doesn't seem to have seeped back in from the intake b/c the TB is clean. So I'm going to say this residue is either from the oil the VR filter comes with stock, or some of the residue could have been from the AirRaid I had been running for a short while a few years ago.
Either way guys....check out your MAF sensor!
5th gen IS SOLD! 6th gen built 10/14!!! Can't wait!!