engine boggs down on accel, o2 sensor code (out of limits) on 1990 BMW 325i

Car has 150 compression on all cyls. hit deep water on highway. drained fluids and checked valves, all ok.Ran perfectly for @2hours and then stalled.Check eng light went on with code for o2 out of limits. Replaced sensor and tried different ECU. Any ideas where to go from here?

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1 answer
if the air mass sensor got hit with water, it is most likely history. it's expensive, so let a BMW specialty shop check this out.