2001 QX4 - P0171 and P0174 and engine surge at idle?

[QX42001POS]

2001 Infiniti QX4 with about 160k miles. It recently started having an engine surge at idle, dropping from ~700 to about ~400-500 for a few seconds before returning to 700. OBDII data shows that it's trimming the fuel back 25% before it surges. Engine is also throwing lean codes on bank 1 and 2.

It's always had catalytic issues, so I'm not sure if that is coming into play here. The only other thing I can think that may have caused it is that I added a can of seafoam to the tank about a week or two before it started.

Does anybody have any experience with this issue? I'm considering replacing the MAF but OBDII data shows it functional at about 4 g/s at idle, and that all four O2 sensors seem functional and consistent with each other. Just want to make my baby better again and fix this issue before it becomes something greater.

[04pathse]

Did you check for vacuum leaks?
Also, maybe try cleaning the MAFS (use CRC MAFS cleaner)

[QX42001POS]

Haven't checked for vacuum leakes yet. How do I check for them? I cleaned the MAF with CRC and it didn't seams to make a difference.