I have been noticing that my car has been rattling and shaking on rough roads more than I remember it used to. Was getting to the point where I thought the six point brace was loose.
Turns out the sub frame bolts had loosened up - now they are tight and what a difference! Even seems to shift better.
If you have not checked yours lately, I highly recommend it!
Also, my car had been averaging 22 mpg in mostly city driving. I did notice I little hesitation under full acceleration as well. Reset the ECU and acceleration is now smooth and milage has increased to 24.5. May be worth resetting the ECU every once in a while.