Two things.

Have you tried a new spark plug yet? Often a new plug will cure hard starting or missing while running. The plug may "look" fine but may not be.

Check the sensor wire for intermittant shorting to the engine case. The insulation can wear against the case and expose bare conductors to ground. The spiral wrap sheathing can help eliminate this but it can still happen. It is always a good idea to restrain the cable to keep it from flopping around and possibly wearing a bare spot or fatigueing the conductors due to vibration.