On February 1, 1997, at 1700 central standard time, a Cessna 172E, N5598T, registered to and owned by the pilot, was destroyed upon impacting terrain shortly after take off near Waxahachie, Texas. The certified flight instructor and student pilot received minor injuries. The instructional flight was being conducted under Title 14 CFR Part 91 when the accident occurred. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported to the investigator-in-charge, that he and his student were practicing touch and go landings at O'Brian Airport, Waxahachie, Texas. During climb out from the second touch and go, the instructor pilot informed the student that he "had a simulated engine failure", and then reduced the throttle. After the student turned toward a field, the instructor increased the throttle, but the aircraft "developed an excessive sink." After the instructor maneuvered to avoid trees the aircraft impacted the ground. The instructor pilot reported that he did not have "very much time" to set up for the forced landing due to the low altitude and close proximity to trees. He added that two pilots who flew the aircraft in the past told him that they had experienced "similar" intermittent power loss problems with the aircraft. After these events, mechanical examinations of the engine by the airframe and powerplant certificated instructor pilot did not reveal any defects. The aircraft wreckage was recovered to Northwest Regional Airport, Dallas, Texas, where an engine examination was conducted under the supervision of an FAA inspector. Throttle and mixture linkages were intact and revealed no defects. After cleaning mud deposits from the carburetor body (impact related), the engine was operated successfully while still mounted in the airframe. The reported power loss could not be duplicated.