First thing to do is try to increase the idle rpm using the idle screw as mentioned earlier. Using a flat tip screw driver turn it half a turn at a time (you will need a 7/16" open wrench to loosen the lock nut on it) clockwise (CW) while listening for increase in engine rpm or watch the tach if you have one. You do not want to go too high for it will affect you gear shifting very badly. You just want it enough to stabilize the engine. If the engine stabilizes, check for misfiring but doing the plug wire pull. When you do the plug wire pull you have to do it rather quickly to avoid damaging the CDM (capacitor discharge module) and listen to change in engine rpm. If the engine rpm slows down that cylinder is firing. If the engine rpm doesn't change that cylinder is not firing. If the engine is firing on all cylinders then it means you just needed to increase idle settings. But there is a reason why you need to increase idle settings, i.e. high carbon build up in the cylinders, broken reed, carb's needs cleaning or because you have exhaust leak inside the cowling. Exhaust leak can easily be diagnosed usually while in the water remove the top cover or cowling and ran the engine. Does the engine idle smoothly compare to when the cover is on? If yes, you most likely have exhaust leaks and you should be able to see it if you look around.
