Engine temperature spikes at idle

HELP! My CR-V's engine just started going from normal to red line in less than 10 second when I idle! I have checked to see that the fans are functional. In fact, the temperature will actually begin to go UP as I hear the fans come on as I idle. There is fluid in the coolant reservoir.

The temperature is high only when I'm idling. When I accelerate, the temperature goes quickly back to normal.

I need to know if this is something I can fix myself or diagnose myself and/or what to say to the mechanic if I have to take it in.

My car is a 1998 model.
Thanks!