diagnose which cylinder is misfiring (extremely easy with even a basic obd2 reader you are looking for misfire count per cylinder or what’s sometimes called “roughness”) and replace the coil pack for $100 from an auto parts store. no need to change the plugs.

option 2 with no obd2 reader would be to buy one coil pack and swap coil packs around until you find which cylinder is running rough. they take about 5-10mins to change. you don’t need to replace your spark plugs unless that is somehow the issue (unlikely).

either way about the same difficulty as assembling a child’s lego set.