2001, 5.4 why does my expedition have no power and reduce milage. on 2001 Ford Expedition

when i first accelerate theres hesitation and choking. my milage has gone down and theres a smell of gas coming from the exhaust. The problem is usually only bad when the weather heats up. The hotter it is outside, the worse it seems to be. any ideas on what it is and is there anything I can do myself to fix this?

Asked by for the 2001 Ford Expedition