Lean mixture happens when there is unmetered air (vacuum leak) or the MAF is reading MORE air than what is passing through it... which is not as common as it not reading as much as is passing through it, which causes rich mixture.

I'd check the whole intake system for leaks starting with the intake boot to the throttle body (mainly the small hose to the idle control motor). And if that is intack with no cracking/splits, I'd suspect the crankcase vent valve (cyclone valve/oil seperator), mainly either the hose that goes from the bottom of it to the dipstick tube, or the internal diaphragm in the valve which would cause a vacuum leak into the crankcase via the tube to the valve cover.

hey guys found out what was causing the two lean bank 1 & 2 codes...lower intake boot was split in a couple of places. Coming from South Carolina to Ohio and cooler temps must have triggered it. thanks for the help. Luckily mass air flow sensor was okay.