Bank1 lean codes generally point to a vacume leak. One of the cheap plastic lines or a t fitting could have cracked and is allowing a leak to take place.
Just so you guys are aware, a problem at the MAF wiring can cause your fuel level sender to not work, as well as the O2. All that wiring runs inline for the MAF to the injectors to the MAP to the 02. If one gets messed up it can throw codes for the others. This is of course only for a wire fault as in scraped / grounding, etc. It may only toss the code for the one that gives it a bad signal first.
Just a heads up. Check that top engine wiring close.... and maybe check for vacume leaks.
-= 2006 - Panasonic 8401U HU - 2 12"MTX Subs - MB QUART dB6500 6.5" components - MTX 2150x AMP - Kenwood 7202 AMP =- AMAZING 1.5L 109HP Manual 5.. :P