Gilbert-99ContourSE

Engine shots off while driving on my 1999 Contour SE. Bought last month with 74k miles. Car shuts off while driving (usually under 30 mph). Starts up with no problems. Replaced battery Replaced battery cables Checked all grounds Replaced alternator Everything worked fine for one day. Engine still shuts off but only occasionally. Now getting P1131 Lack of HO2S1 Switches, Lean Bank Sensor 1. I understand the P1131 but am more worried about the engine shutting off and can't seem to find a solution. The car is in showroom condition and (when it drives), it drives like a dream. Any help would be very very much appreciated.

Engine shots off while driving on my 1999 Contour SE. Bought last month with 74k miles. Car shuts off while driving (usually under 30 mph). Starts up with no problems. Replaced battery Replaced battery cables Checked all grounds Replaced alternator Everything worked fine for one day. Engine still shuts off but only occasionally. Now getting P1131 Lack of HO2S1 Switches, Lean Bank Sensor 1. I understand the P1131 but am more worried about the engine shutting off and can't seem to find a solution. The car is in showroom condition and (when it drives), it drives like a dream. Any help would be very very much appreciated.