Ford - Fusion :: 2006 Creaks Only When Its Warm Outside

I have a real puzzler on my hands. I have a 2006 Ford Fusion with a manual transmission. Its only got around 70K miles on it, since i was not driving it much for the first couple of years after purchase. Around the fall of last year, i was noticing that the car would make a creaking noise, and with time i was noticing it more. The "creaking" only is heard when the car comes to a stop and takes off (like in bumper to bumper traffic). So when the car is normal speed, i dont hear any noise regardless of putting on the brakes.

I have also noticed that the noise would only come during the afternoons (after my car had been sitting in a hot parking lot). In the morning, the car sounds normal and has no "funny" sounds, due the fact that I park my car in a cool garage overnight. The car drives normal no matter the heat conditions, but the noise can be very annoying. I have also recently noticed that you can sometimes hear this noise when people get in their seats of the car.

I have tried to take my car to a mechanic, but they can not find what is wrong. (Unfortunately, I have only been available to take the car in the mornings, so they of course can not hear a problem). The bearings all check out fine, and doesnt appear to be the shocks. My father also knows alot about cars, and this is really stumping him. The only that he noticed is that the engine mount was cracked, so we got that replaced. We were hoping that this would solve the problem, as he guessed that the "creak" was of the engine shifting. This did not solve the problem, but I am glad that we got it taken care of. As far as I can tell, the sound seems to be coming from the front center of the car, and not from a particular wheel.

During the winter here in Houston, I have not heard the noise, but now that its heating up; the "creak" has reared its ugly head again. What can i do?