On July 4, 2023, at 0915 eastern daylight time, an Airborne Edge-X, N147JL, was substantially damaged when it was involved in an accident near Coral Gables, Florida. The sport pilot and passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, after performing a preflight inspection of the weight-shift-control aircraft, he departed Miami Homestead General Aviation Airport (X51), Homestead, Florida, around 0830. After 30 minutes of flying without anomaly, the engine began to “sputter,” then “race up to 6,000 rpm for a few seconds,” and repeat the acceleration/deceleration cycle. The cycle resulted in the aircraft climbing and descending in unison with the uncommanded acceleration and deceleration of the engine. The pilot attempted to regain full engine power; however, the engine continued to “sputter” and accelerate. After about 10 minutes of circling a park hoping the engine would stabilize, he noted no options for a forced landing site and flew south along the coastline toward a golf course. The pilot lined up to land on the golf course and, as the aircraft cleared the final line of trees, the pilot took his foot off the throttle and the engine “immediately stalled.” He landed the aircraft, “but it had too much speed,” and to avoid a marsh area the pilot raised the nose and glided over the marsh. Then, the aircraft touched down in a grass area, continued into a rocky area, and came to rest inverted in a pond. Examination of the aircraft revealed substantial damage to the wings and fuselage. The fuel tank was damaged and filled with pond water. Postaccident examination of the two-stroke engine by a Federal Aviation Administration inspector revealed that both carburetors were contaminated with water similar to the pond water, as well as a white powdery substance and white clay substance. Disassembly of both carburetors revealed no mechanical anomalies; however the internal jet filters were contaminated with a white powdery substance. Examination and disassembly of the fuel metering distribution system found about 10 drops of fuel and no contamination was noted. The diaphragm seals were not damaged and no anomalies were noted. The fuel lines were not obstructed and the fuel filter located on the fuel line between the fuel metering distribution system and the fuel tank did not contain fuel; however, it contained a white substance. Review of the maintenance records indicated that a condition inspection was performed on March 23, 2023, at a total time of 498.9 hours. No anomalies were noted with the engine at that time.