My quad starts up right away with no problem, but won't idle. I use the choke to start it up and let it warm up for a while (about 10-15 minutes). As long as I stay on the throttle it will run, but as soon as I let off it dies. It was sitting in the garage for about 3 months, so I drained the tank and cleaned out the carb. I also just put in a new spark plug and air filter. After all that it still won't idle. Any advice??????