My bronco will not start without starting fluid if it hasn't been started. once I get it started it will start easily as long as its within 10-20 mins of when I shut it off. I have changed distributor cap, button,plugs,wires, fuel filter,map sensor. Once its idling,if I easy on the gas pedal it revs just fine,if I punch the pedal at all it sputters and back fires.any help would be great, also it smells like it is running a little rich.