Pulled out the air cleaner again.
Noticed there were dried leaves up against the screen in front of the MAF sensor. So I cleaned those out.

Cleaned the wire connections, none look corroded.

Vacuum lines look good and were hooked up where they belong.
I have a Mighty Vac tool and want to start testing the vacuum lines. Trouble is, I'm not sure which ones should hold vacuum and which ones shouldn't. There's a whole lot of them and many connected to various switches etc. Probably just better off using the propane or acetelene instead.

Does anyone know if the line that comes off the front side of the intake hose after the MAF should hold vacuum? Maybe that's an IAC valve? This line has what appears to be a check valve about 2" away from the intake hose. It also has a tee fitting that goes toward the throttle body and then to another switch on top of the a/c condensor.

I also noticed when I started the car and moved it back some, the brake booster pump was not cycling. Not sure how often it is supposed to do that, but I'm sure I've always heard it after a cold start.

I checked for a smooth idle with the Scangauge. The car varies between 4 and 8 rpm when idling. I think that's pretty smooth which makes me think that it can't be much of a vacuum leak.

I think it's got to be something I did when changing the air filter last week. It seems way to coincidental that the light came on shortly after that.

I've got to get a book!