What was found
AIRCRAFT WAS GROUNDED: ON TAKEOFF OUT OF DFW , ENGINE #1 VIBRATION AT T.O. THRUST . ON THRUST REDUCTION VIBRATION SUBSIDED BUT #1 EPR FLUCTUATED IN CLIMB POWER ENGINE READINGS NORMAL AT REDUCED THRUST. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO DFW WHERE IT LANDED SAFELY WITHOUT FURTHER INCIDENT. MAINTENANCE ACCOMPLISHED A DFDR DOWN LOAD AND DETERMINED THAT ENGINE VIBRATION WAS NOT THE ISSUE BUT INSTEAD WAS AN EPR FLUCTUATION DURING FLIGHT ISSUE. MAINTENANCE ACCOMPLISHED TSM 71-00-00-810-832-A AND REPLACED THE LEFT HAND PACK FLOW CONTROL VALVE PER AMM 21-51-51. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED. IN ADDITION THE ACCOMPLISHMENT OF HIGH POWER ENGINE RUNS WAS DONE WITH NO EPR FLUCTUATIONS NOTED.