I have the same problem but i have an S13. I tried almost everything within my budget and the only thing that has worked for me so far is a double electric fan, a ram air under the front bumper, performance radiator, lifted hood and no thermostat. I put a new thermostat in and it did the same thing. I also have a front bumper with a big opening. With all of this, it still goes up if i travel too far. Please note that i`ve had my SR for 5 years already.