First you need to find out if the lean condition is real or fake. I have seen coolant fouled 02s reading always lean and mpg of around 2mpg.

Idle MAP is fairly high around 50-53kpa range. With low maf readings and engine speed is always higher than commanded might suggest a vacuum leak. Engine sucking unmetered air.
Bad tune is always possible reason.

Start playing with mode 4 control and you will nailed it pretty fast. Start by going open loop and monitor O2s reading, than start increasing aft target and monitor at what value 02s goes to 700-800mv.

Than you can play with cylinder deactivation. If there is no change in map and rpm when you disable a certain cylinder, it might be a suspect.