All good advice. Start with the air filter, make sure the choke operates correctly and fully opens when warm, and adjust idle mixture. If that doesn't do it, you're looking at taking the carb apart and resetting the float level (and checking for a heavy float), checking the valve for sealing, and/or doing something with the jet sizes. Assuming it's the stock and original carb, that should not be needed. If you need to get inside the carb, get a kit and go through it completely.
