Has anyone come up with a better resolution?

Today, with the A/C on, my truck was worse. The pinging was under regular acceleration; not even a heavy foot. But, again, it did not happen every time. I do have 87 octane in this tank. I cannot see this as being the problem as I have been using 87 octane for the last three years. Why now?

I just don't get it.

Any suggestions? Other than take it to the dealer? Which I am contimplating right now......

Anyone have a service manual, not the ESM, that has a trouble-shooting section? Can someone look up up "engine knock or ping" and let me know what the suggestions are?

Thanks,

Stone