Well i had the same problem with over heating in my 96 RST after I got in a FMIC. I flushed and filled using a 70% water 30% collant to make it run cooler, added 40 below (it's like redline water wetter) then wired both my fans to kick in at the same time. I still have a little problem over heating tho. On a hot day 100+ the thermostat will go to 1/2 on a HOT day like yesterday 115...I was driving with my wife and son w/ A/C and it got as high as 75% driving. When I come to a slow or idle the temp drops down in a few minutes to a tad below 1/2, It must have been the fan mod I did. If your coolant overflows that means it is boiling and it overflows into the tank which then to the overflow tube and outside the car. Happened to me already, you need to refill rite after. I reason I still overheat still is 1) My actual metal bumper is still on (they cut the it to fit the I/C) 2) My clutch is out which makes the engine run harder esp. uphills. TIP: Keep the engine running near the hi-revs 3K+...it keeps the waterpump pumping fas to keep it circulating. good Luck!
