2003 Ford Focus • 65,000 miles

Motor is cutting out at idle, does not die just cuts out at idle only. It has had this problem for awhile now. When this problem started it had 2 trouble codes a PO302 and a P2274.I switched number 2 coil with 3 it has coil on plugs. After I did that the miss fire code went away and the only one is P2274, sensor signal stuck lean bank one sensor 3, but it still cuts out at idle. Why would the misfire code go away and still cut out at idle. Does anyone have a theory on this?
Randy sharp
October 20, 2013.

Clean the mass airflow sensor and the idle air control valve-start here

Oct 20, 2013.