Ive always had a stick trans and never had issues with pinging before due to the way I drive in the upper rpm range, Even with questionable gas.
Now a 3.0 and auto there is no control and creates the perfect circumstances for pinging.
I know the TPS isnt in the best of shape but it is set correctly, EGR is not the issue as I have checked this through.
AFM is unknown at this time but assume since there is no stutter/falloff its ok.
This leves the O2 sensor, I know this was a huge topic in the past about they get weak and dont use any brands other then Denso, I have not checked this as of yet as there is no way to tell is its bad except just plain out not working and throwing a code.
Also it only pings under cruise load and not under excelleration as that would be open loop.
Opinions on O2 sensor being the suspect?