This bike has been giving me trouble since I got it. It won't idle below about 2500, surges a fair bit, and generally just tries to die whenever i'm not cruising. I've dug into the carbs three times now and each time resolved problems (crud in carbs, crud in the air box, various gasket leaks) but can't fix the symptom. It seems to have to do with the air flow at low rpm as it runs rich and gets bad mileage, but i can't find any more crap or vacuum leaks and i'm fresh out of ideas. Buy all new gaskets and jets? Any better or more specific ideas?