I have an 03 civic that keeps running hot. Ive replaced the radiator, water pump, timing, hoses, thermostat (Honda oem), radiator cap. i could drive hours around my city with no problem. BTW its summer time heat down in South Ga. but i can drive around with no issues. soon as i get on the interstate and drive out about 15 or 20 miles out. my temp hand moves up and down bouncing between halfway and up to the H (red lines). if i stop it will run completely hot. the mechanic i took the car too check the head-gasket and said it was good.

seems like the car only runs hot when driving far out

 

Have you made sure the fan actually runs on both low and high speeds properly?

 

Found out it may be the fans. the car ran hot again yesterday. once i cut the car off, i noticed the fans wasn't running but after the temp hand dropped down a little the fans would cut back on and finish cooling the car back down.