What was found
LEFT WING ANTI ICE INDICATION AFTER TAKE OFF, QRH ACCOMPLISHED, WITHIN SEC WING OVERHEAT POSTED, QRH C/W AGAIN. BOTH RT AND LT WING ANTI ICE NOW POSTED AND INTERMITTENT FOR REMAINDER OF FLT APPROX 6 MIN, AND SO ON UNTIL LANDING. WING ANTI-ICE MODULATING AND SHUTOFF VALVES ACFT RETURNED TO DEPARTURE, EMERGENCY DECLARED. REPLACED LEFT WING ANTI-ICE VALVE IAW AMM 30-12-02, OP'S CHECKED GOOD.