A few weeks ago, I was giving my daughter rides around our neighborhood at <15mph, and I was having trouble keeping the bike idling - I had to keep the choke on full. I put some Seafoam in the tank and let it sit overnight. The next day, it started right up, and after warming up, idled just fine. But now the problem has moved to whatever is responsible for keeping the throttle open when decelerating. When I let off the gas, the engine slowly decelerates with a lot of popping/burbling. What do I need to fix/unclog? I'm not looking to marble it, I'm just looking to get everything back running like it was. I imagine it is some kind of vacuum-controlled thingy on the carb.