Almost stall condition

My 98 Grand Am, 2.4L has a code P0118 for coolant temp high input. Once the engine gets warm enough for the fan to kick in, the engine runs very poorly and almost stalls and smells very rich like it is flooding. Also, the temperature gauge does not respond to the engine warming up. Is this possibly the sensor gone bad?
Any help with what the code actually means or diagnosis of these symptoms would be much appreciated.

I would say you have a bad sensor.
Its a cheap part and easy to replace.

Check this out, might help you test the sensor and shows a chart on temps vs resistance values .
Coolant Temp Sensor on 99+ Grand Am Testing (http://www.automotiveforums.com/vbulletin/showthread.php?t=660655)

Should still work for your 98 even though it says 99.
Hope that helps