A JETSTREAM 41 IN CRUISE AT 10000 FT DECLARED AN EMER AND DIVERTED DUE TO #1 ENG PWR FLUCTUATIONS AND VIBRATIONS CAUSED BY AN INTERMITTENT TORQUE INPUT TO THE ELECTRONIC FUEL CTL.

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ON CLBOUT RPM OF #1 ENG BECAME ERRATIC AND WE RAN THE CHKLIST (MEMORY ITEMS FIRST). THEN WE CONTACTED COMPANY REF TO THIS PROB. INITIALLY IT WAS BELIEVED TO BE JUST AN INDICATION SO THE CREW AND MAINT DECIDED TO RETURN TO DCA. ENRTE; THE INDICATIONS BECAME WORSE; AND THE SOUND OF THE ENG CHANGED AND A HARMONIC VIBRATION BEGAN. THE CREW DISCUSSED THIS AND A DETERMINATION WAS MADE THAT ENG PERFORMANCE WAS NO LONGER SATISFACTORY. (OTHER INDICATIONS: TORQUE; EGT; FUEL FLOW; AND FUEL PRESSURE WERE NOW SHOWING SOMEWHAT ERRATIC AS WELL). PER THE CHKLIST AND PROCS; THE ENG WAS SECURED. AN EMER WAS DECLARED; COMPANY NOTIFIED; FLT ATTENDANT BRIEFED; AND AN UNEVENTFUL LNDG WAS MADE AT BWI ON RWY 33L. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PRIMARY CAUSE OF THE ENG MALFUNCTION WAS A STRETCHED AND CHAFFED WIRE SUPPLYING TORQUE INPUT TO THE ELECTRONIC FUEL CTL. THE RPTR SAID WHEN THE WIRE STRETCHED IT SHORTED TO THE ENG AND THE FUEL CTL COMMANDED INCREASED PWR. THE RPTR SAID THE ENG THEN OPERATED INTERMITTENTLY BTWN NORMAL CRUISE PWR AND IDLE. THE RPTR STATED THE SECTION OF FAILED WIRE WAS LOCATED ON THE MOST FORWARD PART OF THE ENG CLOSE TO THE TORQUE SENSOR.