The ECU only reads the oxygen sensor voltage when it's in open-loop mode, which happens at like 73% or more throttle opening. I forget the exact number. Anyway the point is that at low RPM the oxygen sensor voltage doesn't mean crap. Honda used a sensor that would work when they need it to, but doesn't give you any extra tuning value.

The hesitation you're seeing could be from any number of things but I doubt it's from the oxygen sensor. More likely it's a loose vacuum fitting or wiring connection somewhere.