2000 Windstar O2 sensor

Last summer my fuel injector was clogged so we flushed it. Last week my car began stalling and running rough. We had the O2 sensor replaced and the engine flushed. Is is possible that my O2 sensor was bad last summer and caused the carbon build up on the fuel injector?

It may be that the injector cleaning wiped out the sensor .... if it was done while injectors were still mounted to the engine.

This is somewhat related. I notice the wire to the sensor going to the catalyctic converter just hanging there, should it be secured in some way?