I'm running seafoam this weekend since I had a misfire and am curious as to whether I add it before or after my oil air separator. I plan to add it near the PCV valve which runs into the separator, should I just be adding it somewhere after the separator instead?

I have new sparkplugs and coils so I am ruling those out.

I also have a new cat, am I doing any damage to this, I've read so many conflicting things on seafoam, thoughts?