lean bank one and bank two what would cause this on 2001 Hyundai XG300

plugs,wires and coil connectors have been replaced, as well as air and fuel filters. vehicle acts as if its not getting enough fuel, codes of lean bank one and two come up on every test drive.

Asked by for the 2001 Hyundai XG300
These are codes for the oxygen sensors. They are part of general maint. ont the vehicle. If all these parts have been changed, and no other running symptons are present you may just want to clear the codes and see what happens. Often times bad gas can set these codes as well.
My hyundi xg300 doesnt seem to be giving full power when I drive it wat could it be
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Amx 77K miles. Bank 1 Bank 2 both run lean. Showing improper full mixture. I chose the $12 can from Auto-Zone on the MASS-AIR FLOW SENSOR. This sensor is visible to the left of the air box. Cleaning turned the light off. Amx one year later at 81K miles the vehile refuses to start. Towed to dealership. Bank 1 & Bank 2 running lean. Dealership replaced $300 MASS AIR FLOW SENSOR. Check engine light is no longer on.