DII rich left bank stinky exhaust crap idle

[ezzzzzzz]

I drove through flooded streets 2 days ago following a tremendous downpour. That night I noticed a rough idle condition like it was missing one cylinder. The next day the idle issue persisted but did go away a couple of times. This morning it was really bad and the exhaust reeked of rotten egg. I pulled the plugs to find the entire left bank heavily sooted. All were replaced. I then pulled the associated O2 sensor to find it heavily sooty too. I swapped it for a known good one figuring it was the real culprit for the condition. The check engine light never illuminated. Afterwards I took it for a very short drive. The exhaust doesn't reek. It runs better but not nice as before the problem reared it's ugly head. I'm assuming it can be contributed to the coked up cylinders and the ECM having to relearn. Opinions?

 

[ezzzzzzz]

I went for a long drive. The idle is as smooth if not smoother than before. I guess it all pointed to a failed O2. My only curiosity is whether the deep water fording killed the O2 or was it merely coincidence.

 

[distrovol]

Water and oil can make their way into the connectors.

 

[ezzzzzzz]

Yep, but no water in the connector. I'm convinced it was just bad timing and the O2 sensor went out when it did. The truck runs great now.