I have a 2001 Magnum 325 4X4 that started running real bad last year. I was sure it was a carb problem. I replaced several parts, including the diaphram that was ruined from running excess cleaner in the gas. I got the motor running real good. Recently I was pulling a heavy load in low gear at a slow speed and all the sudden lost power. I disconnected the load and was barely able to run the atv into my shop. The engine was sputtering real bad and backfired some. I took the carb off and could not find anything wrong. Put it back together and had same problem. I then bought a carb repair kit and replaced all the needles, after making sure there was no dirt or blockages in the carb. I also put on a new fuel pump and fuel filter, and completely flushed the fuel system. Put it back together, and fired up. SAME PROBLEM!!! I have also adjusted the valves (last year) and checked the compression (good). Motor starts right off. I have noticed that the diaphragm slide valve does not go up when I try to rev the motor. When I lift it the motor starts to sputter real bad. I’m pretty sure I have all the parts in the carb installed correctly, per the diagram. I can sure use some help.