checking connections won't do it. Youll want to pull the plug and make sure its spraking (ground the plug with a screw driver to the block or other metal with a screw driver on the threads and have someone crank at WOT to stop fuel entering the engine). Also check. It may be the spark plug wire as well. Whens the last time you changed them?
Could also be coil went. Or the wiring harness sending power to the coil pack.