ok, was the radiator and or motor ever drained and left drained for any length of time?has the thermosat been changed?it dosnt just over heat when you sitting there spinning the wheels with very low speeds?{dont laugh it has happened many a time with people that dont know you need airflow}.have you had the engine flushed?how many k's on the engine?do you have spotlights?are you running the standard computer or aftermarket?{lean burn etc}.
mick