I have an 85 Bronco 4x4...5.0 EFI. I have a rough running ride, so decided to try the old "pull the wire off while its running" trick. Well...Turns out that #7 is NOT firing. there is spark from the wire, but the plug isn't firing. Now....These are new plugs, wires, rotor, and cap. What next?? Should I try to DECREASE the gap in plug #7??