PA28-235 suffers partial power loss shortly after takeoff. Returns to land opposite direction at departure airport.

Narrative

Accelerated; rotated and began slow climb out from Runway XX (7;000 FT length). At approximately 800 FT AGL; experienced significant reduction in engine power. Power was not completely lost. Established glide; executed emergency procedures (tanks; e-pump; mixture; throttle; magnetos). With 800 FT AGL; and better than 90 KTS airspeed; simultaneously began turn back toward airport. Full power restored within a few seconds. Despite full power; contacted ATC anyway during turn; declared emergency based on loss of power; requested immediate landing on Runway XY (reciprocal of Runway XX). ATC cleared immediate landing successful landing; with rollout and taxi clear of active runway. Airport personnel responded with emergency equipment; and followed plane to ramp. Successful engine shutdown. Emergency crew assisted with inspection to confirm no fire. Fuel on board estimated at 3 hours 30 minutes of 7 total hours duration: Left Tip = 03 of 17 gallons. Left Main = 15 of 25 gallons; Right Main = 15 of 25 gallons. Right Tip = 10 of 17 gallons. After taxiing to the ramp; all tanks were filled; and a sustained; uninterrupted; full throttle run-up was completed for 10 minutes. No reduction in power was observed; but engine sounded much better than during previous run-up prior to takeoff.