The pilot reported that after leveling off at 2,300 feet near the destination airport, the engine quit. Attempts by the pilot to restart the engine were unsuccessful. During the emergency descent for the forced landing over a wooded area, the airplane collided with trees then the ground. Examination of the engine by an FAA certificated mechanic revealed that a section of the intake gasket at the No. 3 cylinder assembly was missing. This resulted in unmetered air entering the cylinder resulting in a lean fuel/air mixture. The No. 3 cylinder was removed and the top compression ring and oil control ring in the piston land could not be moved. Additionally, the top of the piston and cylinder corroborated the lean mixture. The pilot reported that several months earlier, the cylinder head temperature (CHT) was high but it was determined that the CHT probe was broken. The CHT probe is installed on the No. 3 cylinder. Review of the engine logbook revealed that on December 5, 1991, the intake gaskets were replaced.