My 01 4.8 started to ping a little early this year so i went from 87gas to 89gas and the problem went away. Should say symptoms went away. So now i go back to 87 gas just to see and the ping is back. Just a little maybe a few times a week. Where should i look to start with?

 

Winter blend gas maybe?

 

Is it stock?
Never heard one ping when you let off the throttle.

 

And at times just when you get back on it. It is stock for now. Soon to have heads,cam,tune... or a 6.0