2005 Mitsubishi Endeavor Spark Plug Coils

First of all thank you so much for your donation.Yes if one of your coil's is bad it would cause that cylinder not to run.As far as damage from that it's putting a strain on the engine from that cylinder not firing and throwing the engine off balance.Also if that cylinder isn't working your putting extra fuel in the catalytic convertor and will damage it and there really expensive.So i would get it fixed right away.I can't give a time frame when damage happens i can only tell you to get it fixed right away.