On a 1998 Ford F-150 : Check the Vehicle Emission Control Information ( VECI ) decal located at the front of your engine compartment ( it will show what type of spark plug to use , and the spark plug gap )
For a 1994 Ford F-150 5.0 L V8 engine : One of Fords websites shows ( .054 inch spark plug gap ) * see if there is a Vehicle Emission Control Information ( VECI ) decal in the engine compartment , it will show what type of spark plugs to use and the spark plug gap *
Did you set the spark plug gap to factory specs? A plug gapped to wide will cause hesitation. Also look and see if you inadvertently disconnected a vacuum hose. You may need to replace the plug wires on this 10 year old vehicle.
ok buddy. here is the thing. when it came time for me to change mine. i looked and looked and could not find one. they are extremey hard get out because you dont want to break the spark pluge coil. each spark plug has its own. it would be alot easyer for you if you took it to the ford dealer ship.