i have a 1992 mazda 323. when it is cold the idle wanders up and down, from what i would consider a normal level to a very high idle , once it warms up the idle evens out to a normal level. also, it takes a while to warm up ( the temperature gauge climbs all the way up to the top, where it stays for awhile, and then falls to the correct level), and then once it is warm, the heat blows cold, unless i am driving at a speed consistently above 50-60km/h. I think this may be a thermostat issue. it seems to me like the thermostat is not working correctly, in that it doesnt open soon enough (allowing the temperature to climb all the way to the top), and then once it is open, it does not close, which keeps the heater from working correctly. it may also be some kind of sensor issue, i am not entirely certain.

thanks ahead of time for your help.