The pilot stated that he was conducting a skydiver "jump run", and prior to letting the skydivers out the radio squelch interrupter failed causing a constant static noise. After letting the skydivers out over the airport the pilot set up the descent based on the winds acquired for the previous landing on runway 22. As he circled for landing the manifold pressure indication "dropped off" to zero. The pilot was unsure if he had a partial power loss or a gauge failure. He could not hear or feel the engine indications because of the static noise on the radio squelch and descent profile, so he committed to a power off glide path for his approach. The pilot stated that the airplanes approach speed was about 100 knots prior to the threshold for landing. The airplane touched down beyond the threshold and as the pilot applied full braking the airplane "ballooned" back into the air. The pilot attempted to stop the airplane but was unsuccessful and exited the runway, coming to rest after colliding with a ditch. An examination of the airplane revealed that the empennage and firewall was buckled during the landing sequence. The airplane was equipped with a JPI engine monitor and review of the data did not reveal a loss in engine power during the flight. The wind reported from a nearby weather station revealed that winds were 010 degrees at 6 knots at the time of the accident.