Look at the Bank 1 check valve. Make sure the vacuum hose is connected and that it holds vacuum.

 

Bank 1 (1,3,5,7) is the right (rear) cylinder bank. The AIR valve is the black dome bolted to the top of the cam cover. Both AIR valves sometimes carbon up from exhaust gases. Can be cleaned with TB cleaner, replaced with junkyard pieces, or new from RockAuto.

Here's the vacuum schematic. Remove the engine beauty cover and check the AIR solenoid and vacuum lines.

See the un-numbered thingy next to #3? That's a VDV (Vacuum Delay Valve) and the inside line drawing is an indicator of which way it is installed in the vacuum line. In real life the valve may have a white or yellow end cap.

If any of those plastic vacuum lines is broken, the line and its rubber connectors can be replaced with proper sized rubber vacuum hose from any parts store. Take a connector boot with you for sizing.

 

Thank you Submariner,

I check for possible rubber cracking/obvious items, and found none.. with the exception of how easily the rubber connector (female) came off the tip on the item next to #3

The code went away for now on its own.

I keep getting the MAF code, even though I've cleaned the thing often... gives me rough performance/poor gas mileage

 

Maybe it's time to REPLACE the MAF sensor.