According to the pilot, he serviced the 1949 Stinson 108-3 with 24 gallons of automotive fuel on the morning of the accident flight. He checked the fuel for the presence of water or debris, performed "a simple alcohol test," and noted no problems. The engine started "perfectly," and he did not note any anomalies during the runup check. At the beginning of the takeoff roll, the engine power was "good," but once airborne, the engine began running "unusually." The pilot looked down at the tachometer and noticed that the rpm had decreased by 300. He checked that the throttle and mixture controls were both in the forward position. As the engine power continued to decrease, the pilot knew he could not turn the airplane back to the runway and would not clear the tops of the trees ahead, so he flew toward a gap in the trees. He attempted to keep the airplane flying as long as he could, but ultimately it entered a "controlled stall," and descended into a power line. The airplane then impacted the ground, erupted in flames, and was consumed by a postimpact fire. Examination of the remaining portions of the engine revealed no evidence of any preimpact mechanical deficiencies. A sample of fuel from the container used to service the airplane was examined, and found absent of debris or water.