What was found
WHILE ENROUTE STL TO UIN AT ALTITUDE OF 4,000 FT THE RT ENG EG AND TORQUE INSTR BEGAN TO FLUCTUATE. A/C YAWED AND CONT'D TO DO SO. NORMAL PROCEDURES WERE FOLLOWED AND ENGINE REMAINED UNCONTROLLABLE. RT ENGINE WAS SHUT DOWN. CREW DECLARED AN EMERGENCY. A/C LANDED SAFELY AT UIN WITHOUT FURTHER INC. ENGINE RUNS PERFORMED, UNABLE TO DUPLICATE PROBLEM WITH TTL COMPUTER OFF. CREW MEL AND THE TTLAND A/C CONT'D IN SERVICE. ENG/S/C HAS HISTORY OF FALSE TEMP. & TORQUE INDI (9/20 &9/24/00) A/C RET TO STL ENG RUNS & INSP OF INDICATING SYS PERFORMED NO DISCREP NOTED. A/C ARRIVED MQY FROM STL & TTL VALVE REPLACED/MEL CLEARED. A/C WILL RETURN MQY FOR FURTHER TROUBLESHOOTING/INSPEC OF ENG INDIC. SYS.