OK...My car will heat up fast, as usual. If I don't turn the heat on when I start it and drive it will heat up to half and blow not a bit of heat. Once this happens the car will over heat badly. If i stop and shut the engine off, and start it back up (with heat on) the heat gauge will go down and it will blow heat again. If I stop and idle the car, I will loose heat every time, until I get up to a steady speed. It has only over heated a couple of times, but EVERY TIME I stop and idle it looses heat. I have read other forums, but not exactly the same thing that is happening here...thermostat?

 

Please see this thread: https://honda-tech.com/forums/honda-civic-2001-2005-78/01-05-civic-cooling-system-q-overheating-fans-inoperable-etc-2889523/