Overheating No Matter What I Do!

2001 4dr ls 2.2 New radiator thermostat serpentine belt. Thought it may be fan but I jumped it and works checked relay and was fine also the fuse. One weird thing is if i leave the car in park and let it run hot it will kick the fan on at around 240 degrees but if i floor the gas pedal it begins to cool down. I'm at my wits end and cant understand why in park when i give it gas it cools down. Thinking of replacing water pump(3 yrs old) and the engine coolant temp sensor any other ideas and any idea why it cools down when i give it gas??
Desperate,
Thank u all:banghead:

as long as your temperature guage is working your coolant temp sensor is fine, it could be either your water pump, which usually starts leaking coolant slowly out the weephole when they start going out (or at least mine did), or you didnt bleed all the air out of your system when you replaced your radiator or thermostat, which also could very well be the problem, i had a similar problem when i just replaced my water pump, all i did was loosen that little bleeder screw for a minute, you dont even take that screw out, it just opens up a little valve on the side, and you do it with your engine OFF, it will be painfully easy on your 2001 2.2