As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ENGINE #1 DURING RUN UP TO 50% N1, ENGINE LAG WAS GREATER THAN 50% OF ENGINE #2. ONCE STABLE NO LAG OCCURED TO TO POWER. THE LAG TIMEWAS SIGNIFICANT. MAINTENANCE ACCOMPLISHED AN OPERATIONAL CHECK OF THE ENGINE AND DETERMINED THE ACCELERATION WAS WITHIN PARAMETERS.