Scott, thanks for the insights. I have RC injectors as my OE ones quite back in 05. I may have time this weekend to do the flow charts that are listed in the "Intermittents" section under Detonation/Spark Knock. Just to be clear, it's not setting a DTC when the knock happens, it's not even giving me a "winking" SES light.
I bought some SeaFoam to add to the gas....just as a look see as I can't figure out what harm that could do in a dilute form. I'm rather embarrassed to say that my car may not be properly driven enough and I have allowed too much carbon to be built up?
Tom