2005 Pontiac Grand Am gasoline smell

My car has a very strong odor of gasoline when it starts up. The odor will go away after about 5 minutes of having the car running, but will come back if the car sits idle, like at a stop light or in heavy traffic. This just started about two weeks ago. I don't know if this contributes to the problem, but the car also runs hot if it sits idle. If I am stuck in traffic my car temperature will start to rise rapidly but will go back down if I begin to move again. Could the gasoline odor cause the car to catch on fire? Please help if you have any information.