I'd go a step further and use a laser temp gun on it and see which cylinder is running cooler during miss fire...I've had good success with that method,also I've used a ignition lead tester(snap-on). Last method is a pair of very well insulated pliers and pull a lead at a time to find miss...I'm not a fan of that way, got a few good jolts over the years no matter how carefull I try to be!