Sounds like the #1 spark plug wire may not be seated fully onto the plug. That or the #1 spark plug connector was damaged when you pulled it off the old plug so it may need replacing now. Many aftermarket ignition wiring sets are shoddily constructed so perhaps it just pulled apart. For me, I stick with the factory OE ignition wiring set. Well built, holds together, and doesn't cause radio static like some aftermarket ignition wiring sets can.