Check the fuel pressure regulator for proper operation with a pressure tester. The only other thing I can think of is a clogged injector (stuck open), which can also be tested with the pressure tester. If you notice the pressure drops to zero quickly after shutdown, that would indicate a leak somewhere in the system. This would explain the gas odor. Hope this helps.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch