I think you have two unrelated problems. I think Tom is right about the fuel pump check valve. The fuel smell which I don't think has anything to do with the starting problem could be the EHA or other hose leaking.

Cigar
Did you replace the o2 sensor or did a shop do it? I do not see how an o2 sensor can affect a cold start since the car is in open loop and doesn't even know the o2 sensor exists.

Peter

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