your better off using a genuine ford part thermostat. i never like the "pattern" ones.

mondy v6's are prone to overheating.

try thoroughly flushing and back flushing the cooling system and radiator.

are you sure both fans are kicking in? they are notorious for seizing the fans.

otherwise, are you sure the temp sender is accurate and that the car is really overheating? when the temp guage needle rises high, do you experience bubbling and steaming from the header tank?

or it could be head gasket failure. i'd try the above, then get the heads pressure tested.