Ok before I get jumped on the reason I did not add this to a previous post is because if your like me alot of times you search title only&when I looked up info for this nada came back so hopefully this will help the next guy.
Well I just did my cap&rotor well the rotor was kind of dark&the cap had corrosion built up on the inside where the terminals are.Im wondering can this cause a misfire?I would imagine.What else?And what causes this?

 

Yes it can cause a miss, High voltage arc/transfer between to points of metal. If it's green moisture in the cap.