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5.0L (1979-1995) MustangTechnical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.
Are your plugs properly gapped or are they fouled? When she bogs is there a puff of black out the back, does it ping, how's your gas mileage? Throw a can of seafoam in it at half tank or less of low octane, take a good long trip, and check your plugs after. Don't know without seeing it, but if you are having misfires it could be plugs, carbon build up, or too high of octane fuel. Make sure your plugs are not gapped more than recommended. If you gap them .005" less than nominal and the problem goes away, stick with that gap.
A full tune may help a lot if it's been a while. Plugs, wires, cap, rotor, oil change/filter, and fuel filter is a good idea as well as the Seafoam...I've heard it works wonders for cleaning crap out of an engine.
First thing and cheapest way is to replace your air filter, pcv valve overall tune up if necessary. If that doesn't solve your problem then look into something else.