ignition coil

As long as the wires are good and the spark plug gaps are correct, the coil won't cause a single cylinder misfire. I'd start with a compression test. Next, if you have multiple injectors you might have a bad one. I don't like throwing random parts at a problem so I'd start with a cylinder balance test to see which cylinder is misfiring. You can do that by grounding spark plug wires one at a time to see which one doesn't cause a drop in rpm. Once the dead cylinder is identified, swap that injector with one from a different cylinder to see if the misfire goes to the other cylinder.