Okay, so after having had lean bank 1+2 codes again for the past few months, I found out that the MAF was "in need of replacement" again. I had already replaced it once in 2014 for the same exact issue. This time I removed it from the car and inspected it. Sure enough, there was oily crap all over it.
I love my GruppeM intake, even if it keeps fucking up my MAF. The sound is too intoxicating, but man do I hate the fact that aftermarket air filters like this use oil. What an idiotic design.
Since my MAF was "trashed" anyway, I had nothing to lose, so I went on a quest to find CRC MAF cleaner. I didn't want to use anything not designed specifically for MAFs, so it had to be this particular product. Walmart didn't have it. Advance Auto didn't have it. AutoZone, however, did.
Since everyone that said they have sprayed their MAFs said that they did little sprays here and there and went easy on it, I decided to do the opposite in the name of science. So, I doused the shit out of this thing, making sure every nook and cranny on the inside tunnel of the MAF was sprayed. I let it dry, and did it again, thoroughly spraying every single inside area including the sensor and the upper plate where it mounts. I let the whole thing dry overnight and installed the next morning, subsequently clearing the codes for my test run.
This was on February 22. It is now March 4th, having put 1000km on it since then, and the CEL is still off. I'm genuinely surprised, and now have to start wondering how long this will actually last. I'm going to see if this will last 'till my next oil change (which I'm severely overdue for one now anyway, so I'll reset the clock when I get it).