AN F100 FO EXPERIENCED A #2 ENG ROLLBACK TO FLT IDLE. 5 MINS LATER; THE ENG SOMEHOW RESTORED ITSELF AND WORKED PROPERLY FOR THE REST OF THE FLT.

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WE WERE DSNDING FROM FL350 TO FL330 WHEN #2 ENG ROLLED BACK TO FLT IDLE. WE WERE IN THE CLOUDS WITH ENG AND WING/TAIL ANTI-ICE ON. THERE WERE NO INDICATIONS OF ICING. BOTH THROTTLES WERE ALIGNED. #1 ENG/THROTTLE WENT TO MAX CLB PWR AND #2 ENG INDICATIONS WERE IDLE PWR WHILE WE CONTINUED THE DSCNT TOWARDS 15000 FT. THE STANDBY ENG INDICATOR VERIFIED THE PRIMARY ENG INDICATIONS ON THE MFDU THAT #2 ENG WAS NEAR IDLE. VIBRATION INDICATOR WAS NORMAL. #2 ENG WOULD NOT RESPOND TO MOVEMENTS OF #2 THROTTLE. WE HAD A SLIGHT YAW OF THE AIRPLANE CORRECTED BY RUDDER. AFTER 5 MINS; ENG CAME BACK TO FULL PWR AND WORKED PROPERLY THE REST OF THE FLT INTO ORD. AFTER LNDG; WE WROTE UP THE #2 ENG. ORD MAINT PERSONNEL TOOK THE AIRPLANE OTS AND SAID THAT THIS AIRPLANE HAD NOT HAD THE FUEL CTL UNIT MODIFICATION FOR THE F100 AND THAT THIS TYPE OF ENG ROLLBACK COULD HAPPEN. I BELIEVE THAT MODIFICATIONS AND PROBS LIKE THIS SHOULD BE COMMUNICATED TO THE FLCS SO THAT WE CAN ANTICIPATE THESE TYPES OF EVENTS AND RESPOND PROPERLY. LACK OF PROPER INFO TO THE FLC THAT THE COMPANY KNEW ABOUT COULD HAVE BEEN VERY USEFUL DURING THIS EVENT.