You may have broken a wire in the connector between the coil pack and the plug. If the plugs have been in the engine for a good while and you had to do a lot of twisting and pulling to get the boot to release from the plug, you may have broken a connector. One at a time, disconnect the lead that goes to each individual coil pack and note if there is an RPM drop / change in engine sound. If disconnecting a lead leads to a drop in rpm, that plug is firing. When you disconnect one that doesn't cause a drop you've found the cylinder that is not firing. Make sure the engine is off before you disconnect the lead. Poking around the one of the coils with the engine running may knock you on your ass.