Do you have an electric choke or a manual choke with a choke cable? Does it run better when it gets warmer, worse, same? I think on some carbs you can adjust the choke, but i don't have much experience with electric chokes, so i don't know how. Like PKRWUD said, try cranking it and seeing what the plugs look like before it starts up. I've tried to start my '84 (which has a manual choke) without putting the choke on and it does the same thing that you're car is doing.
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previous name: 84stangLX
'84 Mustang 5.0 LX
my LX
'89 Mustang GT
my GT