Stock I6 should not need Premium fuel. If you must run a high octane, you can even cut back to 89.
Another thing to look at is exhaust leaks. Many a small "tick-tick-tick" that increases with RPM turns out to be an exhaust leak. Could be at the donut seal.
Gary
EDIT: I thought I was seeing double... I was in the engine and drivetrain section and saw this post and couldn't figure out where my response was.

No real need to post in multiple forums.