The AFC manipulates your MAF signal, both allowing you to target a more appropriate AFR (and thus making more power) AND avoiding fuel cut (at least to a degree).
Its funny looking back at the MSP now I feel like if there was a real proper tuning solution available the car would have a LOT better reputation. I've been tuning my car now for the last couple of months, and after I got my air/fuel dialed in, I started tweaking my spark tables (yes tables.. I believe all told thus far I have tweaked about 25 different tables, and that is not counting the ones that were altered when I started, as I worked off of a canned tune for the mods I have done). The ECU keeps thinking it hears knock (I'm cammed so it sounds different, we call this false knock), so I had to dumb down the KR sensitivity a bit, but I have SO much control over the ECU that I can basically spend the rest of my life re-touching the tune to make it both safer, and more efficient. The MSP is SERIOUSLY handicapped in this way, and all of the guys on here (I'm not trying to offend, so please don't take this wrong) who are changing out intercoolers, intakes, exhaust, etc and don't have a tuning solution (If I were to do it over again, I would have an SSFTC at an absolute minimum so that I could tweak spark and timing for both safety [read:detonation] and power reasons) at all are at MINIMUM leaving a lot of power on the table, and likely putting their already fragile engine in jeopardy as well.