ECU is perfectly fine. most of time on a 96-97 accord when you see the D3 or D4 blinks, that mean that you are having problems with the shifting selenoids. B4 u take that out and replace it, check and look for a fuse that is call alt speed sensor. most of the time it can be the fuse. On your temperature gages.. Your gages is probably mess up.. someone try to take it off and try to mess with it.. the needle is probably stuck somewhere.. OVERHEATING PROBLEM.. you can change the fan the radiator or watever.. itll still do the same thing.. If you are using a aftermarket radiator cap, what you need to do a little modifying on your cap. the seal/gasket is what making the car overheat. cut off the bottom and center seal. it will help alottttttt.