When I am geting on the freeway and geting up to 70mph, if I step on it (no mater what gear I am in), and put it all the way to the floor, it sounds like somthin rattles, untill I let off the gas a little and then it goes away.

Could this be knocking? I have recently switched to lower octane gas ($) and I switched back to regular oil instead of synthetic. Can this be the cause of what I hear?

I have heard a motor knock when its not running alright, and at idle. But I have never heard it under hard acceleration. It sounds like a high pitched clicking vibration. Hard to say what it sounds like on here.

What do you think?

 

If it's knocking, it should do it in every gear and not JUST at 70mph, I'd bet it's just something that is shaking because of the speed that you are at..