Things I have done: New aluminum radiator from Man-A-Fre (stock size) high flow 160' thermostat, new water pump, tried two different manual fans with aid of small electric fan, different shrouds, burped system, 20 pound cap, timing is dead on, and finally put in a different 350. any hills or idle will run to 230' before I sut it down. It really hates to sit and run at all with out overheting. My question is if there is a chance that the water is running through the motor to quickly??? I have acually tried three different thermostats. If it is running through the radiator to quick what do I do to slow it down????? Or any other ideas would help. By the way the motor is not pumped up at all.