On July 23, 1994, at 1530 central daylight time, an Acro Sport, N869M, sustained substantial damage when it made a hard landing after losing engine power immediately after taking off from Albert Lea Municipal Airport, Albert Lea, Minnesota. The private pilot, who was participating in an acrobatic competition at the time of the accident, received serious injuries. The 14 CFR Part 91 flight operated in visual meteorological conditions. According to one witness, N869M departed runway 34 (4501' x 100') and leveled off approximately 150 feet above the ground and 1200 feet down the runway. At the same time that the airplane leveled off, the witness states he heard a reduction in engine power. When the airplane reached the end of runway 34, he observed the airplane make a steep to medium bank to the left. The witness did not see the airplane impact the ground, but does state that he did not hear any backfiring. The airplane was at reduced power, and stayed at the same RPM the entire time that he was able to hear the engine. A second witness first noticed the airplane shortly after takeoff, level at approximately 150 feet above the ground and operating at reduced power. The witness states that the pilot had approximately 2600 feet of runway remaining at the time when he leveled off. He states there was no indication of a rough running engine or any visible smoke. The witness states he expected the airplane to land on the remaining runway, but the airplane continued. He then states that the pilot initiated a left turn while maintaining altitude. At the conclusion of the turn, at approximately 75 feet above the ground, the witness observed the airplane's nose pitch down slightly, the sink rate increased dramatically, and the right wing dropped slightly. The aircraft impacted the ground in a 15 degrees nose down attitude. The witness states there was no change in engine sound throughout the occurrence. A postaccident inspection of the engine revealed the number three fuel injector was plugged with a small amount of an unidentified matter.