On August 23, 1994, about 0945 eastern daylight time, a Cessna 152, N6088H, registered to Comair Aviation Academy, nosed over in a field near Osteen, Florida, while making a forced landing following loss of engine power, while on a 14 CFR Part 91 instructional flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the commercial-rated flight instructor and private-rated dual student were not injured. The flight originated at Sanford, Florida, on August 23, 1994, about 0845. The pilots stated that they had performed a simulated engine out with a descent to about 600 feet. At 600 feet a "go-around" was initiated and full engine power was obtained. When climbing through 800 feet the engine retarded to idle without warning. Attempts to regain engine power were unsuccessful and a forced landing was made in a field. During landing rollout the aircraft nosed over on the soft ground. Postcrash examination of the aircraft was performed by a FAA inspector. The engine was started and operated only to about 1,000 rpm. The carburetor was replaced and the engine operated to full power. Examination of the carburetor indicated that a foreign object about 3/32 of an inch in diameter was located in the mixture metering sleeve and blocking the pickup for the fuel discharge nozzle. The foreign object was identified by magnification to be part of an insect. It was determined the foreign object was too large to have passed into the carburetor through the fuel inlet screen. The carburetor had been overhauled in October 1993, and installed on N6088H on August 5, 1994, 50 flight hours before the accident. See Component Inspection Report. (The location is different from what was reported on the Preliminary Report, Aviation.)