As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 4 ENGINE, AFTER SETTING POWER FOR CRUISE, NR 4 ENGINE ROLLED BACK .15 EPR. EGT, FUEL FLOW N1 AND N2 ALL DROPPED. THROTTLE DID NOT MOVE. REPLACED NR 4 ENGINE FUEL CONTROL UNIT IAW 73-20-01. REPLACED NR 4 LOW PRESSURE FUEL FILTER. PERFORMED LEAK CHECK OF NR 4 ENGINE LOW PRESSURE FUEL FILTER ON ENGINE RUN. LEAK CHECKED GOOD.