Cut some vacuum hose, and make extenders between the coil towers, and slip over the wire terminals. I only do 3 at a time, (one bank). The ignition KV travels right up the vacuum hose, so plugs keep firing. Now carefully take a grounding probe, or (small/medium screwdriver, with a jumper lead, to a good ground) Touch each vacuum hose extender. This will kill that cylinder, and you will hear, and feel the drop in rpm. Make sure your screwdriver is well grounded, and not near any other wires, or electrical components!