What was found
WE ENCOUNTERED AN AREA OF HI CLOUDS AS WE ENTERED THE AREA LIGHT TURBULENCE WAS ENCOUNTERED & A NOTED TEMP OF -51 SAT. LIGHT MOISTURE WAS OBSERVED & THE ENG ANTI-ICE WAS SELECTED ON. LIGHT ICING WAS OBSERVED INCREASING FROM MODERATE TO HEAVY & A TEMP OF -41 WAS NOTED. WING ANTI-ICE WAS SELECTED ON, NO SIGNIFICANT RADAR RETURNS WERE NOTED. AT THIS TIME A RT WNG ANT-ICE VAL EICAS WARNING MSG ILLUMINATED. THE RT EPR INDICATOR WENT TO 0 & THE RT ENG POWER STARTED TO FADE. THRUST LEVER COMMANDS WERE INEFFECTIVE & OUR AIRSPEED STARTED TO DETERIORATE. WE EXECUTED AN OFFSET MANEUVER, DECLARED AN EMER WITH SFO ATC ON FREQUENCY HF 17904 & STARTED A SLOW DESCENT, RECEIVED AN ATC CLEARANCE TO FL220, SEL MAX ALT, MAINTAINING A SAFE AIRSPEED. WE REFERENCED THE QRH ENG LIMIT SURGE OR STALL CHECKLIST & CYCLED THE WING ANTI-ICE. THESE ACTIONS CLEARED THE EICAS MSG & WE OBSERVED A SLOW RECOVERY OF EPR & THRUST TO THE RT ENG. AS AIRSPEED RETURNED WE LEVELED AT FL 360. REQUESTED & RECEIVED AN AMENDED CLEARANCE TO MAINTAIN FL 360. THE ACFT RETURNED TO NORMAL OPERATION & THE EMER WITH SFO ATC WAS CANCELLED.