On January 27, 2000, about 1630 eastern standard time, a Cessna 150L, N11567, registered to and operated by Carolina Flight Institute, Inc., collided with terrain during a forced landing shortly after takeoff from the Statesboro-Bulloch County Airport, Statesboro, Georgia. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 instructional flight. The airplane was substantially damaged and the certified flight instructor (CFI) and student pilot were not injured. The flight originated about 1600, from the Plantation Airpark Airport, Sylvania, Georgia. The flight departed with full fuel tanks and the CFI stated that after takeoff, the student performed airwork then proceeded to the Statesboro Airport where the flight entered the traffic pattern to perform touch-and-go landings. The first approach and landing were uneventful; the student applied full power to takeoff. During the climb out about 100 feet above ground level, the engine began to run rough, backfire, and, "...we lost almost all our power." The CFI took the controls and verified that the mixture, carburetor heat, and throttle were full forward, applied full flaps, and landed on the runway. With insufficient runway remaining to stop the airplane and obstructions and a downsloping embankment ahead, the CFI applied full throttle; the engine only partially responded. He then intentionally stalled the airplane into a marsh where the airplane came to rest upright. After recovery of the airplane, the damaged propeller was removed and a serviceable propeller listed in the airplane type certificate data sheet was installed. An impact damaged fuel line at the gascolator was bypassed but the remainder of the fuel delivery system was used. The engine was started in the presence of an FAA inspector and was noted to run rough during engine warm-up. During the magneto check at 1,700 rpm, engine backfiring and loss of engine power was noted. The engine was then secured and started again. During the second run, no discrepancies were noted; the engine ran smooth at 1,700 rpm.