My mower has been surging all season and the mechanic at the dealer said there is no carbuerator rebuild kit avail. I think I have a 23 or 25HP Kohler. Now today I broke the throttle cable and got it replaced and now it is running very rough and losing power in tall grass. Also, it is blowing black smoke when I engage the blades. I'm guessing carbueration, but if there is no kit available what do I do, but a new carb?