I HAVE A 06' FORD FIVE HUNDRED THAT I PURCHASED CERTIFIED USED IN 07'. WITHIN A FEW MONTHS I STARTED EXPERIENCING SURGING PROBLEMS ESPECIALLY WHEN THE A/C WAS RUNNING. THE DEALER REPLACED THE INSTRUMENT CLUSTER IN 08' BUT DID NOT FIX THE PROBLEM. ON EACH RETURN TO THE DEALERSHIP THEY COULD NOT FIX THE PROBLEM. ON MY LAST VISIT TO THE DEALER THEY CLEANED THE THROTTLE BODY AND SAID THAT WOULD FIX THE PROBLEM. THIS DID NOT FIX THE PROBLEM AND THEY COULD NOT DIAGNOSE THE PROBLEM. THIS PROBLEM HAS CAUSED ME TO REAREND A VEHICLE IN 2009. FORD IS NOT RESPONDING TO THE PROBLEM AT ALL. AFTER 3+ YEARS OF TRYING TO FIGURE OUT WHAT THE PROBLEM IS I ALL BUT HAVE GIVEN UP. THAT IS UNTIL TODAY WHEN THE REPAIR SHOP THAT I USE ON A REGULAR BASIS HIRED A NEW MECHANIC WHO WAS ABLE TO DIAGNOSE THE PROBLEM. THE PROBLEM TURNS OUT TO BE THE THROTTLE POSITION SENSORS IN THE THROTTLE BODY. IT TOOK THE MECHANIC OVER 2 HOURS TO GET TO THE BOTTOM OF THE PROBLEM. THE UNFORTUNATE THING IS THE COST OF A NEW THROTTLE BODY IS OVER $500 THEN ADD LABOR. IF I HAVE THE THROTTLE BODY REPLACED THERE IS NO GUARANTEE FROM FORD THAT THE NEW THROTTLE BODY WON'T DO THE SAME THING. IT IS OBVIOUS THAT FORD HAS A PROBLEM WITH THE THROTTLE BODY AND IS NOT WILLING TO RESOLVE THE ISSUE AND BACK THEIR PRODUCTS. *KB