Hi Guys. So my jet ski was running rough yesterday so i put brand new ngk laser platinum plugs in it. After that it ran great. Today, however i tried starting it and it was running rough again. It was like is was skipping and coughing. i took the plugs out and they were really black and carboned. i cleaned them the best I could with a dry cloth and it ran a little better but it still doesnt get to its maximum rpm and speed. Im thinking its running a little rich but im not sure if that is the only problem. any help would be great. Thanks.