Hello and welcome to just answer. Your after market parts will not cause a misfire on cylinder # XXXXX You have a misfire due to an ignition problem, fuel injector problem, or low compression. The first thing you need to rule out is a compression issue, so do / get a compression test on all cylinders. They should all be within 25 lbs of each other. If # XXXXX is lower than the rest, then something is going on like a burnt valve or other mechanical problem. If the compression is ok, then try new plugs and maybe swap the #3 fuel injector with another cylinder. If the misfire moves to the other cylinder, then you will need to replace the injector.
I hope these tips will help you figure this out, and let me know if you need further assistance with this.
Thanks! I will do just that!
You are welcome Pete, and good luck my friend,
It was a bad plug. The electrode was burnt completely down....is there something that causes this?...just concerned there's another problem brewing that may have caused it....or just defective plug?