Overheating Neon ???

i have posted some previous issues and had great success with your guys/girls help. I yet again have another issue that is plaguing me. (1998 Dodge Neon SOHC) Every once in a while for quite some time now, if you let the neon idle in park, the temp will spike up pretty rapidly to high temps, like temps that set the vehicles warning buzzer. If you throw the car in drive and take off, it'll drop back down to normal temp relatively quickly.

This has happened 2 times in the last week, and before that, i can remember like 2 or 3 times in the last several months. I tried letting it run when at home to try and diagnosis the problem, but i left it running a good 30 minutes, and it never went over normal operating temp.

Anybody have any input??

check your anti freeze level
check for blockage in the system
check to make sure your fans are working
check to make sure you coolant temp sensor is opperating properly
check your fan relay if fans are not working