As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MIA - CREW REPORTED DURING CRUISE MACH WINDOW AIR SPEEED KEPT INCRESING. TURNED OFF AUTO THROTTLE AND REDUCED THRUST BUT AIRSPEED WOULD NOT REDUCE. ABOUT 1 MINUTE LATER AIRSPEED BEGAN TO SLOW. FLIGHT RETURNED MIA LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT AIR DATA COMPUTER. SYSTEM GROUND CHECK NORMAL OPERATION.