Did you give the 93 octane a chance to make it to the injectors. What I mean is, if you started with half a tank of bad fuel and then added good 93 octane, than you have a full tank of crappy 93 octane now. I'd keep my foot out of it so it won't ping and go for a long drive to get rid of that stuff that is in there and then fill up when you're almost empty, that way you'll have all good gas getting to your engine and a minimal amount of junk. It's another easy thing to try without breaking out the tools....unless you consider a gas card or your wallet a tool of course. 8) Is it pinging all of the time, when it's under load, or just at WOT?