Run some SeaFoam through the brake booster line (read up, link below).
Clean the throttle body, remove the EGR valve and clean out all the carbon. Replace the PCV valve and inspect its hose and elbows for cracks.
Etc. Bottom line, you should NOT have pinging on regular grade gas. Using higher octane to ease pinging is a bandaid, confirming that something is wrong, and a waste of money. I ran a 180* thermostat for a while, but it didn't ping when I put the 192* back in. I think the 180 contributed to the carbon build-up.
Remember the 3.0 is happy with high rpms, which helps keep the carbon from accumulating.