pos 3.5 ohc

i got one for someone out here with more experience with these pita's . got a 96 intrepid for a company car for one of the routes and it keeps pumping antifreeze out of the front timing cover . have had the water pump replaced twice along with the belt tensioner , replaced the thermostat , the funky "block" on the back of the engine with all the freaking coolant lines , tha reserve tank , flushed the system three times , ran two leak down tests to check for a bad head gasket , on and on . after you fix the pump it will run for a little while trouble free and then boom she over heats and starts pumping it out the front again . any one got any insight into these damn things it's driving me crazy and i've got to much invested in it to throw it away.