I have a nissan 240sx that is overheating. I have replaced the thermostat, water pumps, and radiator. The system was flushed before and after the radiator was replaced. The coolant boils as soon as the needle begins to go alittle above the normal height. I recently replaced the radiator and when i took it for a test run it was fine. I left the car running for about 5 more minutes and i got back into the car and it looked like the needle was alil higher but my car has been overheating for months I forgot where normal was suppose to be. By the time I got to the end of the driveway, it began overheating again. Every time after this the car does overheats. If it idles it doesnt overheat as fast it needs to be driven around and then after driving around when you stop it begins to overheat. The same symptom keeps repeating after every different part was replaced. The thermostat was the first to be replaced and yes it was put in correctly taken out and put in correctly again. I dont know of any others options of why this car keeps overheating. If you have information please help!!!