chasing down a misfire(carbed)

[sketchy90z71]

So can anyone help me understand how a misfire can go from rare and hardly noticeable to consistent and irritating just by changing the cap and rotor on an hei? I'm stumped and don't see how new parts can make a problem worse. My truck was running pretty ok aside from an off idle hesitation before this and that's a whole other story (maybe accelerator pump or power valve) but this sudden misfire is on my nerves

 

[Black_cirrus]

Internal damage to the plug wires or a bad connection. Bad parts. Loose contact of the wire to the cap. That's the quick list. Spray a mist of water from a spray bottle when it's dark and see if you see any arcing near the cap and along the wires.

 

[sketchy90z71]

Ok I know this may be a dumb question but can the oil leaking from my bad valve cover gasket onto the plug boots cause a misfire like this? I'm just trying to work from simple stuff first