Pull the wire out from the hole and see if it is wet. If the people that did the tune up didn't seat the boot correctly you can get water in there and cause a miss. If it is dry check for spark. If you have spark check the plug just in case if they didn't replace that one. If it is good move on to your injector and check to see if you have pulse. If you have pulse then swap injectors with another cylinder. If the miss jumps, replace the injector. If it doesn't change, do a compression test.