clunking

Whenever I break or accelerate I get a clunking noise coming from what feels like under the center of the car. I know that sometimes where it feels like it's coming from and where you think it's coming from it isn't because noise and vibration travel.

I have checked all the motor mounts and they look fine, I have checked and nuts and bolts I can see for tightness and they're fine, I am totally stumped. I would like any ideas if you have them before I take it to the mechanic.

In the past the only thing I have done is brake pad replacement and front stuts.