ALL types of gasoline contain detergents. As we've discussed a million times on here and all over the net, it's pointless and damaging to put higher octane in an engine designed for lower octane unless you have modified significant or your engine is significantly damaged (IE timing off).

Rotating gasolines frequently is the only thing you can do with gas, since they all have different kinds of detegents.

But I digress...

Have you taken your plugs out and inspected them for visual damage/unusual wear?
Ever clean the EGR port?
Ever use a top end cleaner, like seafoam? How about a fuel system cleaner like Lucas (seafoam works here too but Lucas is probably the best)?