[denverpete]

If it's something that "only you notice" then it might just be your brain playing tricks on you. Sometimes that happens after a vehicle is in the shop.

New plugs did work for me - but we're talking performance degradation that anyone would notice. They attempted to clean the plug but apparently it was too far gone.

Like MNB says, probably not a bad idea to get them replaced. No, it's not cheap if you have it done. Nothing on a Porsche is cheap if you have it done.....