Why is my car overheating while idling? on 2000 Mitsubishi Galant

After I have been driving for a while and my engine has had sufficient time to heat up, my car begins to overheat while idling. As soon as I accelerate, the thermostat needle falls back into the mid-range. This problem was previously diagnosed as a bad water pump. I had the water pump replaced a year ago and it fixed the problem, up until recently when the same exact thing started occurring again. Is is possible that my water has gone bad again? If so, is there another issue that may be causing this? I don't want to have to replace it every year!

by in Saint Charles, MO on January 25, 2013
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3 answers
ANSWER by , January 25, 2013
your thermaste needs to be replaced
ANSWER by , January 25, 2013
are your cooling fans working and did you have thermostat repl when w/p was done? its for sure a coolant flow issue
ANSWER by , January 26, 2013
Turn the A/C on when it's idling and get out , open the hood and make sure the fan(s) are on. If not bring it to shop for diagnosis and repair.