What was found
AIRCRAFT WAS GROUNDED: URING CRUISE FLIGHT, WEATHER RADAR WAS VERY INTERMITTENT AND SPORADIC WHEN SHOWING RETURNS ON BOTH CAPTAIN'S AND FIRST OFFICER'S MFDS; RADAR WOULD PAINT RETURNS FOR A MOMENT AND THEN GO BLANK FOR SEVERAL SECONDS (SEE ATTACHED VIDEO); EVENTUALLY RECEIVED AN AMBER "PWS FAIL" AND AN AMBER "WXR FAIL" ON BOTH CAPTAIN'S AND FIRST OFFICER'S MFDS. DECESION MADE TO DIVERT TO DFW AND EMERGENCY WAS DECLARED AND AIRCRAFT LANDED WIHTOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED WEATHER RADAR RECEIVER/TRANSMITTER PER AMM 34-43-41, OPERATIONAL TEST GOOD PER AMM 34-43-00.