What was found
ETOPS, CREW REPORTS #1 ENG STALL , RETURN TO BLOCK, MAINTENANCE COMPLETED BORESCOPE INSPECTION, NO DEFECT NOTED, ENGINE KEEPS STALLING DURING RUNS. PERFORMED TSM 71-00-00-810-854-APAR , 4.A (1) TO (3) STEP, PERFORMED BORESCOPE INSP OF HPC & LPC PER STEP 4.A (4) TO (5), PERFORMED STEP 4.A (6) TO (10), NO PROBLEM FOUND. REPLACED VSV ACTUATOR PER AMM 75-31-02 , HP BLEED VALVE IAW AMM 36-11-51, PRV IJAW AMM 36-11-52, LEAK CHECK GOOD. BORESCOPE HPC OUTER SEALS AND INNER AIR FROM STAGE 4 TO 8 IAW AMM 72-35-00-290-801-A, SENT VIDEO TO POWERPLANT ENGINEERING. R & R BUFFER AIR VALVE PER AMM 75-26-02. LEAK CHECK GOOD. ACCOMPLISHED POWER ASSURANCE TEST IAW AMM 71-00-00 SYSTEM CHECKED NORMAL, OK FOR SERVICE.