What was found
TPA/MIA - FLT 4937 - PILOT REPORTED INDICATOR FOR NR 4 FUEL FLOW WAS FLUCTUATING AND HANGING UP. AIRCRAFT WAS FERRIED FROM MIA TO FLL AFTER INSPECTION AND MAG STICK CHECKED FOR FUEL QUANTITY. MAINTENANCE REPLACED NR 4 AND NR 5 FUEL TANK PROBES DUE TO HIGH RESISTANCE READINGS. INSULATION CHECK AT FUEL TANK CHECKED OK, BUT NOT AT COCKPIT INDICATOR. FURTHER TROUBLESHOOTING INDICATED NR 4 FUEL FLOW CANNON PLUG HAD CORROSION AND LOOSE PINS. REPLACED CANNON PLUG AND SYSTEM TESTED OK. CAUSE OF FLUCTUATING DETERMINED TO BE FAULTY CANNON PLUG LOCATED ON TANK NR 4 BEHIND RT LEADING WING EDGE. CHECKED ALL ASSOCIATED WIRING TO PREVENT RECURRENCE.