I have a 1993 honda fourtrax 300. It idles great but dies under a load, it acts like it is starving for fuel. I cleaned the carb and started it with the air cleaner off so I could see if the piston in the carb flutters up and done or stays steady at a higher rpm. It stayed steady which indicates the diaphram is ok, but I noticed an occasional misfire in the carb. Any suggestions as to what the problem is. THis has been driving my buddy and I up a wall.