I suspect that in the formulation of our current foreign policy there is a machivellian belief that if we can uninstall Saddam, we can install a friendly secular government that will be more open to us with their oil and which can then effectively neutralize Saudi Arabia's economic influence over us.
So, our goal might be to establish another government, with oil reserves, that is friendlier to us than Saudi Arabia?

And the reason to do this would be to neutralize Saudi Arabia's hold over us which is based upon oil?

This is why I say that it always comes back to oil in the mid-east.