I know the new gas is crap, but does it make that much difference? 2000 Intrepid R/T 3.5 107K
I run synthetic 10w30 and have upgraded to Shell 93 with no improvement. I was under the impression that the 'brand' gasolines have additives to help with crappy gas. Also, shouldn't the computer compensate for detonation or a lean condition?

Knock sensor may be bunk.

egr could be stuck open too

Try some Techron fuel additive in the next couple tanks of gas. I used a little Mopar combustion chamber cleaner down the intake and the techron in the gas and it got rid of my pinging on my non mopar.

Would the knock sensor or EGR turn on the 'check engine' light? Mine is not on and there are no codes stored or pending.

With no codes or CEL, I'd think possibly excessive carbon build-up. I'd try Seafoam or plain water added very slowly through a vacuum line. Don't add too fast or you risk hydro-lock.

If it pings at mid throttle but not when wide open, I'd look at EGR not working.

Knock sensor was my first thought, and EGR is also possible. You mentioned switching to Shell 93. If you had been running cheap gas for a long time, you could easily have the deposits that others have mentioned. I've heard good things about Mopar Combustion Chamber Cleaner, but have not used it personally.

I like the Seafoam idea, but where can I locate a vacuum line that feeds the intake? There is a place where I can put in between the throttle plate and the intake. Will that work?

If there's a vacuum line in between the throttle plate and the intake that should work. Also maybe you could use the vacuum line to the brake booster.