Too much air? The engine should stay running even without a filter, so I'd say too little air was the problem you had. The filter might've been too restrictive for the engine, so try a bigger filter.
...either that or the old filter WAS restrictive, and the carb was intentionally detuned to somehow keep it running with that restriction. This would also mean you weren't getting the best performance before, and the tuning of the carb will get you much better gas mileage.
-Boyo
