2001 Toyota Corolla Engine pinging

First off, thanks for the help.

My car is detonating badly between 3k rpm and and 3.5k rpm. I have replaced the MAF sensor, spark plugs, air filter, and Oxygen sensor. There is no engine check light of any kind. I have taken it to a Toyota dealership and they were stumped. The told me to run a bottle of engine cleaner through the gas tank. That didn't fix anything. I also ran a can of seafoam through the intake manifold to help with carbon build up. That didn't work either. What should I do next? Thanks for the help.
Sincerely,

Bryan