1998 Acura CL Car makes rattling sound when accelerating/de

I just recently bought a used 1998 Acura CL from a car auction, manual drive.

This is my first car, let alone, my first time driving stick.
Since I've had it, it took me a week to get stick shift down.

And since the day I bought it, when I speed up, or slow down even downshifting, my car makes a metallic rattling sound.

I put the needed level of octane gas it it, so its not the gas. Could it be my exhaust?

Help! I don't know all the little mechanics behind cars!