What was found
(CAN) AT FLT390, 25NM FROM DOWNWIND OF A THUNDERSTORM, IN LIGHT CLOUD, LEFT HAND ENGINE EXPERIENCED A SURGE, CHECK LIST CARRIED OUT, THROTTLE RETURNED TO CRUISE POWER AND EXPERIENCED A SECOND SURGE. DESCENT TO FL350, ALL PARAMETERS NORMAL. CREW ELECTED TO DIVERT INTO DENVER. ENGINE INSPECTED, 3.0/3.5 BLEED VALVE CHECKED NO METAL, HIGH POWER RUN CARRIED OUT. CONTINUED SERVICE.LEFT HAND ENGINE CHANGED. ADDITIONAL INFORMATION WILL FOLLOW AFTER INVESTIGATION. 2000-10-25 TC:AWAIT TEARDOWN FROM OPERATOR. 2000-11-07TC: REPORT RECEIVED SPECIFYING LPC TURBULENT AIRFLOW DUE TO FOREIGN MATERIAL,EEC HARNESS AND RELAY ANOMALIES, ASSOCIATED ALT AND WEATHER CONDITIONS AS CAUSE TO DUAL SURGE EPISODE.