So my wife was driving around my 2000 Rav4 the other day and it started "smoking" she says. She added water to the radiator and got it home. I just bought this car from craigslist and I dont know any history about the cooling system. I decided to do a complete flush and fill the system back up with proper coolant and fluid levels. In the past couple of days, when I am at idle the temp gauge on the dash goes up into the red. When I drive or accelerate, the temp gauge goes back to the middle where it is supposed to be. I havent seen any smoke or steam at all. Anyone have any idea what is going on? Thank you for any help or advice!!