The commercial pilot practiced taxing the airplane for about a ½ hour before he attempted a takeoff and landing. After landing, he decided to practice a runway "speed up and down" to become more comfortable with engine settings. During the first "runup", he applied "very light throttle input," but the engine increased in power "very fast." The airplane made a sudden left turn, and the left wing dropped close to the ground at a speed of about 35 - 40 mph. The pilot was unable to regain control of the airplane with applications of right rudder and changes of engine power. The airplane veered off the runway, up an incline, struck the airport perimeter fence, and impacted terrain. The airplane sustained substantial damage to both wings. A quartering tailwind prevailed at the time of the accident. There were no mechanical anomalies that would have precluded normal airplane operation.