prelude help

Hey was wondering if anyone could give me some help. I have a 1992 prelude s, it's the first non american car i have owned. I have had problem with it since i got it. The latest of which has me completely stumped. The car say it is over heating but isn't, but it only say this when it is idoling. Once you start moving the heat gauge goes back down. Also when the car idols it starts to die and i have to rev itto keep it running. and then once i get to where i am going the fan wont stop running, and it kills my battery. If anyone has any clue what it could be please let me know. I don't know very much about imports, i have always had muscle cars.