Perhaps somehow, due to high condensation in the engine compartment, your two main module plug-in inside the black boxs nexts to the battery have excess build-up of moisture. A very simple solution in this case is to purchase some contact cleaner from your local electronic store. Disconnect the negative portion of your battery before during any work. Open the top lid of the enclose case and slide up the P.C.M.. Inspect for any type of moisture. On it, you will find a ground strip and two black connectors. Unplug and disassemble one connector at a time by removing the back cover with a small screw driver to allow trap water to escape and wash it down with the contact cleaner. Let air dry thoroughly, ( Or use an air hose) and be sure to reassemble it to the same way as the second cable connector is to avoid confusion. Once you had completed all work, test your cable by hooking them up, (Will only connect to their own socket) and ensure that everything works. Once you had determine that the misfire had stopped while the engine is running, go ahead and turn off the vehicle, disconnect the battery and disconnect the cable. Lubricate both pin connectors with a noncorrosive\non-conductive grease to form a good seal against future moisture buildup. Reassemble and you should be O'K.