I drive a jeep grand cherokee and the fifth cylnder is misfiring. what would repair cosy be?

sounds like a cracked spark plug you can check this by your self and it will only cost u the price of the plug usually about 2.50. All plugs are easily accessable just make sure to remove only one at a time and reinstall after inspected so you don't forget which wire went where. you will be able to see a crack in the porsalin on the plug once located easy fix purchase and install. Total cost 15 min. of your time and 2.50 out of your pocket.