tomklipp is right. my first suggestion would be to check the mechanical speed control if that is what you are using. If not, check the trim on your radio. If it is trimmed to full forward, you may not be able to control it. If you are using the mechanical speed control don't forget to check your servo. it could be stuck in the wide open position. If none of this helps give us a little more info on your setup and maybe we can help you trouble shoot more.
