We have just replaced the radiator cap, fan clutch, water pump and thermostat in my 2004 ford explorer and it is still overheating. The radiator was also flushed. In addition there is no heat coming out of the heater. I don't know if it related, but the air does not blow out of the inside vents all the time. It is intermittant. It appears the water/coolant is not always flowing as it should. Sometimes it appears to flow normal and sometimes it doesn't. The car overheated when the heater vents were changed (heat to feet, face, defrost, etc) and when the temp was raised and lowered. We are at a loss. Any ideas?