I'm a big believer in STP Complete Fuel System Cleaner in the silver bottle. I have used it in all of my fuel injected vehicles at some point. It stopped the pinging in the low performance mini-van and the dakota. Each vehicle has over 100,000 miles and the injectors have never been off the car to be cleaned.

Now be prepared for more posts saying that I don't know what I'm talking about and "that stuff doesn't work, it's junk use ________ instead". Which will, in effect leave you no closer to finding a solution than you were before you posted.

Hope this helps