I just purchased a 2000 ZX-6 with less then 5000 miles and am having troubles with keeping it running. The person I purchased it from only put 100 miles on it last year. At higher RPM's it seems to have good response but is doggy and will stall at low RPM's. Even while driving on the highway while running 5000-6000 RPM, it starts to spit and sputter and will loose power. I've taken the carbs out and checked and cleaned the jets and put fresh fuel in but still the same problem. I have a new fuel and air filter on the way hoping this will help and the plugs were changed by the seller when I picked it up. When the carbs were off, I could see a lot of carbon build-up on the valves. I called a local mechanic and he suggested having "the carbs. syncronized and ride it hard to get the carbon off. If the carbs. are clean and the fuel is fresh, it shouldn't need a valve adjustment with this few miles." Does anybody have any suggestions? I'm slowly learning how it all operates.