What was found
APPROX 20 MIN INTO 2ND FLT, RT ENGINE ROLLED BACK TO IDLE DURING CLIMBOUT / LEVEL OFF AT 8900 MSL FOLLOWING LOW APPROACH. ROLLBACK WAS ACCOMPANIED BY SIGNIFICANT VIBRATION BUT NO ANNUNCIATORS. CREW BROUGHT RT THRUST LEVER TO IDLE, DECLARED AN EMERGENCY AND CONTINUED CLIMB TO 13,000 FT W/ RT ENGINE AT IDLE AND LEFT ENG AT MCT. LEVEL AT 13,000 AND 250 KIAS RT THRUST LEVER WAS BROUGHT UP TO APPROX 71 PERCENT TO MATCH LEFT. REMAINDER OF 20 MIN FLIGHT TO KBOI WAS UNEVENTFUL WITH ALL ENGINE PARAMETERS NORMAL. THE AIRCRAFT LANDED UNEVENTFULLY.