What can a defective oxygen sensor do to a car?

Ok, I have an 1981 corvette and i found a senor, that i beleive to be and oxygen sensor, just dangling. But before i even looked for it, The car sounded to miss, after it warmed up. But only when at low rpms. I know its not the carps or spark plugs. Any advise on where the sensor goes, I looked everywhere and can't find where it goes. ( I'm not a mechanic, just broke to take it to a garage)