Bigkev,
Some surging is a normal part of life with the KX5. It typically is noticable when the throttle is chopped and you are coasting or after reving the engine up while in neutral. Consider it a sign that your jetting is close to optimum (which is good) and goes away when your bike is rich (which is bad). Unfortunately you just have to get used to it. If it surges on it's own while idling it means that your pilor jet is too lean or there may be an air leak. My 92 is one of the worst for surging but I don't notice it any more. I rarely use engine braking when I ride. Check your jetting with the jetting chart. The chart is spot on. To make snotty downhills fun, have a look in the "riding tips and tricks" section. Enjoy your K5. With a few minor mods they are a wonderful bike. Hope this helps. Cam.