My 94' honda civic vx (1.5 L V-tech e) has 230,000 on the body, but only about 60,000 on a rebuilt engine. Will drive and, according to the gauge, maintain a steady and normal temperature while driving on most roads, climbing steep hills at high rpms, idling, but then if I take corners fast, usually going downhill, the needle will steadily climb up, and it wont stop even if I bring the car to idle, or if I slow down, or go straight, most everything has been tried. Coolant: full. Another weird thing: The heater blows cold air during these occurences.
If you stop, turn off the car and let it cool off a long while, it usually is fine again, until you take corners again.
Simple system but I have to eliminate the water pump. I would flush the system and take special not to care for the radiator. If something is going to clog it will probably be the radiator. Replace that thermostat as well. Very cheap and easy.