Replaced all four spark plugs after my car began to 'studder'. SP 2 is still misfiring. SP 2 is also the one that had obvious burn/scorch marks as well as the ignition coil. The 'studder' is a lot less noticable but still present.
Ideas?

 

I think that your next step is to consider replacing the coil pack.

 

I had similar issue and found I forgot to reconnect vacuum hose.....