Hi. I have a Husqvarna self propelled.... upon initial start up for this season, it started, but was chugging, then stopped... then I flooded it priming it... waited it started, same thing.. restarted and while working the throttle-- it seemed like it needed more gas-- and when I tried to "rev her up" that killed her immediately. Changed the spark plug, checked gas line, all seemed fine... Started right up, but chugging... like a miss, exactly the same as before but would run, roughly at idle... Again, gave it some gas and she stalled. What do you think this could be?