2003 Corolla Engine Noise....

Hello,

I have a 2003 Toyota Corolla S Manual with about 64000 miles. I was wondering if anyone can help me out with my situation. Many thanks in advance.
Every time I hit the accelerator around 3000rpm (every gear), a weird rattling sound is heard in the engine while i'm driving. Once the car is up to speed with 3000rpm, i tap the accelerator to keep my speed constant. Nut everytime i tap the accelator, u can hear the rattling noise again. Any advice on how to remedy this will help a lot.


Thank You!!!

Valve adjustment.
Tune-up.

If the above two don't work, try higher octane gas.

does the valve adjustment have to be done by a mechanic, or that something i can do on my own?