01YZ250f, bike starts fine, runs with choke pulled. Once I push the choke in, the idle speed drops and the bike stalls. If I hold the throttle up bit the bike will run, choke in, for a few seconds, then I hear a slight pop in the carb and it stalls. I have the main screw set at 1 3/4 turns to 2 turns(tried both) with no change. Its about 35 degrees today.