On August 21, 2003, approximately 1110 mountain daylight time, a Cessna 150F, N8065F, registered to and operated by the pilot, was substantially damaged when it impacted trees during a forced landing 30 miles west of Laramie, Wyoming. The private pilot, the sole occupant on board, was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the cross-country flight being conducted under Title 14 CFR Part 91. The flight originated at Skypark Airport, Bountiful, Utah, approximately 0800. According to the pilot, he was in cruise flight at 10,500 feet when the engine began running "rough." Power dropped below 2,000 rpm. He tried but was unable to restore full power, and made a forced landing in mountainous terrain. The airplane struck several trees, destroying both wings and bending the main spar. Density altitude at Laramie was calculated to be 10,312 feet msl. On September 24, 2003, the engine was functionally tested to 2,475 rpm. The magnetos were tested and functioned normally. No mechanical anomalies were noted.