It's gotta be one of three things. Spark, fuel, or air. I'm guessing that adjusting the idle screw won't do anything, but give it a shot. Your eacv could be all clogged up, and causing some of it... But if those are fine, and you're getting fuel, the it's got to be something spark related. I'd just run over everything and be thourough... Does it stutter at all?