According to the pilot, he completed his "descent checklist" and moved the fuel selector from the "Right" to the "Left" position. The airplane was 2 to 3 miles from the destination airport when the engine "began to quit" and then completely stopped producing power. The pilot adjusted to best glide airspeed and attempted "as many immediate action items [from] memory as I could." The pilot completed a forced landing to an interstate highway which resulted in substantial damage to the fuselage. Examination of the airplane revealed no evidence of pre-impact anomalies or fuel leakage, and about 35 gallons of fuel in each wing. The fuel selector was found in the "Off" position; however, it was not determined if it had been moved to that position in flight or subsequent to the flight. Recorded engine data revealed that about 1 minute prior to touchdown, the fuel flow rapidly dropped to almost zero, all exhaust gas temperatures went to zero, and all cylinder head temperatures began a gradual decline. Under the supervision of an FAA inspector, a club propeller was installed to replace the damaged propeller for a test run of the engine on the airframe, using the airplane's own fuel system. The engine started immediately, accelerated smoothly, and ran continuously without interruption when either the "Left" or "Right" positions were selected on the fuel selector. The engine stopped producing power approximately 1 minute after the fuel selector was placed in the "Off" position, which was located to the left of the "Left" position.