What was found
AIRCRAFT WAS GROUNDED: DURING TAKEOFF ROLL AFTER 80 KTS WE HAD AN AIRSPEED UNRELIABLE.CAPTAIN AND STBY ISFD SPEED WERE AT 125 KTS, FO SPEED WAS STUCKAT 80 KTS AND THEN 40-45K DIFFERED FROM CAPT AND STND BY INDICATIONS. MAINTENANCE REMOVED AND REPLACED FO PITOT PROBE IAW AMM 34-11-01, AND ACCOMPLISHED TEST, 34-11-00-790-806,34-11-00-790-807, AND ADM TEST 34-21-00-710-801, AND ACCOMPLISHED CAT-3 STATUS SYS SUCCESSFUL.