I would say that the low end is too rich or too lean. It depends what it does when it quits. if you try to open the throttle and it sputters, it could be too rich, if it shuts off sharp it could be too lean. Try the pinch test. If you're not sure what that is, it's just pinching the fuel line while the engine is at idle. The rpm's should rise before the engine quits. That's what I would look at first.