i got a tough one for you. i have an 89 gl that has an intermittant overheating problem.when i it start it up ,and sometimes when i accelerate i can hear water wooshing thru the heater core.it dosnt overheat all the time.today i drove it 5 miles it overheated. i let it sit then drove it 40(freeway) miles and it was fine.after sitting i drove it around 20(freeway) miles and it started overheating again i pulled over let it sit drove off and it overheated again.i let it sit then drove off it ran fine the rest of the way home(in traffic). there dos`nt seem to be any rime or reason to this.ive already replaced the thermostadt. any ideas? thanks rob