[IROC]

Update: Finally got my scan tool hooked up and it is only showing one code - the P0420 (catalytic system efficiency low or something like that). Reading on the inter webs, the water is still a little muddy, but the factory service manual says that a P0420 is either 1. Exhaust leak, 2. Bad A/F sensor or 3. Bad cat. My exhaust looks like new. The truck has 119k miles (a little more than I previously thought) and many people claim that the rear O2 sensor (A/F sensor) is a prime culprit at this mileage.

I am going to keep an eye on it and when the CEL comes on again, I'll be able to see what the code is real time. The truck is running much better, so I'm assuming my MAF cleaning was both needed and successful. The scan tool also has the ability to read the O2 sensor output, but I haven't figured out how to do that yet..