you don't know what your talking about or not useing the correct tools or a good cleaner.
O2 doesn't cause a single cylinder misfire normaly, it can though.
what kind of plugs did you put in it when you replaced them?
also i would swap the coil first because its easier then an injector.
spray carb cleaner all over the intake on the bank that has the problem, smooths out then you need to replace the intake gaskets with the updated style.
answer those questions and we'll go from there.