It is very unlikely that the problem is due to an oxygen sensor.
I could be a dirty fuel injector.
The BEST over the counter cleaner for this that I have found is Berryman's B12 Chemtool in the metal can.
Treat a tank of gasoline with the correct amount (if the can says it is for a 10 gallon tank.....you will need 2 cans for a 20 gallon tank).
Another fuel related problem could be (less likely) low fuel pressure.
The computer does not monitor fuel flow or fuel pressure, so it will not give any code(s) for any issues with that.....
Another possibility is that a spark plug wire got damaged in the change process.
The "Check Engine Light" (CEL) will flash when the misfire is taking place.
If they CEL is on but not flashing and has the misfire code stored....it means that it detected the misfire, but it is not happening right now.
This hint is to help you to determine if this is happening all the time or just sometime.
A flashing CEL is an indication of a problem that can damage the catalytic converter.
If the misfire is due to lack of spark....it can cause raw fuel to pass from the cylinder into the catalytic converter.
If this is a persistent problem....it can burn out the catalytic converter.
If the misfire is due to lack of fuel, then there is no fuel to pass on through into the catalytic converter.
The PCM (computer) does not know the cause of the misfire so it will flash the CEL on and off.