would a bad o2 sensor do this?

yes it could be an 02 sensor, or mass air flow, or bad gas, or anything.....if the check engine light is on, hook it up to a computer

The scan code is reporting an 02 sensor because of the misfire, not because of a bad sensor. You probably have a bad / plugged injector. I'll presume that the items you replaced were check and they were good.

See if you or a mechanic can connect a historical scan tool and take it for a drive. This may show why it runs ok at certain times and not at others.

Sounds like a problem with the number 4 cylinder to me. Maybe a defective fuel injector for that cylinder, or perhaps even just a poor electrical connection to that injector. If the fuel delivery system is ok, then there may be an internal problem with that cylinder since you have replaced all the other stuff. Maybe a compression check would reveal some pertinent information.

did this problem happen al of a sudden or did this happen after work was performed on this engine? is the miss fire all the time or under load while driving down the road ? dont have enough info. to help. But make sure the spark plug wiress are pushed in properly specialy at the distributer cap new wiress especially swap wiress if you have to and look at the old plugs do they all have the same coloring at the tips light brown.or are they black? hope this helps you

no, o2 sensor won't cause a misfire code. I've seen intake leaks, EGR's, overtightened or loosened engine valves, coils, ECM's, injectors all cause this. Goodluck. Loose connection at an injector, wiggle and see if it acts worse.

I had one of those engines. Mine had no compression after 25k miles. What a piece of junk. You getting blue smoke on startup?