well i was driving to work the other day and when i parked my car i noticed that the car was over heating. the needle was a lil more than 3/4 of the way up.i checked the coolant and it has plenty, the fans are working well. another thing i noticed today when i got home it was overheated so i reved the engine up to 5 rpms and the needle dropped to half way. wtf????? anyone have any idea on what it might be? im thinking it might be the thermostat but i can be wrong. anyone have any ideas?
thanks

BTW i am a little crunched for time right now so i dont have time to do a search that will last me 4 hours.