Oxygenated Gas
Part of your problem could be oxygenated gas. I don't know where you live, but it seems more states than just California are using this stuff.
I experienced a pinging problem on my cross country trip last month. I talked to SuperChip, and they suggested using octane booster. I tried it, and it reduced the problem. It did not eliminate the problem, though. Considering the cost, I'm sure you wouldn't want to use octane booster all the time. You could send the chip back, and have them reprogram it - basically, all they need to do is retard the timing. You will loose some of the power/hp, but the pinging will stop.
Now that I'm back in Georgia, running Amoco 93, the truck runs great!