What was found
AFTER SWITCHING TO VNAV, WE RECEIVED VERY STRANGE COMMANDS FROM THE AUTO THROTTLE AND THE FLIGHT DIRECTOR. THE AUTOTHROTTLES WOULDN'T INCREASE TO FULL POWER AND THE FLIGHT DIRECTOR WAS TELLING US TO GO DOWNWARDS; HOWEVER, WE WERE AT 1700 FEET AND 140 KTS. AUTOMATION DISCONNECTED AND LEVELED AT 4000. DECLARED EMERGENCY, LANDED WITHOUT INCIDENT. PERFORMED OPS CHECK OF FMS AND AUTOTHROTTLE.