1996 Kawasaki STS, ran great for an hour or so, the RPM's started falling off, no power wouldn't run much above an idle. When it would go dead, I could choke it to flood it with gas, would run great for about 5 seconds then back to not much above an idle. Took the carbs off last night and checked them, they are spotless inside. all the diaphrams looked good as well, didnt see any the appeared brittle or cracked. Did find the the shims under the carbs, did not have any gaskets with them. Could this have been causing my problems, or is there another way I should look??