I just put a 4.3 in a 95 runner and when I first start driving it will run up to between 230 and 250 and then drop down to 165.I just replace the thermostat and it is still doing the same thing.I am running a straight blade fan and 2 aux electric fans with the factory radiator this is begening to worry me for I dont want to ruin the engine.any help will be much apprciated