If Al Qaida hates America and Americans so much...?

becuase they're are suunies and the terrorists are Shiites....or the other way around, and those to fractions don't like each other.... why, i don't know

I believe they are fomenting trouble to show that they have NOT been beaten and can do anything they want to stir up more trouble for the country and in particular the US. We claimed that we went in there to liberate Iraq from a tyrant and destroy WMD which never existed (at least they've never found any). Our soldiers did eliminate Saddam Hussein but in the process have created mayhem by destroying their infrastructure and being unable to halt the terrorism caused by Al Qaida who continue to frustrate the US efforts.

It's the heretical doctrine of "takfir", where it is permissible, during the carrying out of Jihad, for Muslim to kill Muslim. Al Queda does not only hate the crusader nations. They are also engaged in acts to help topple the regimes of the Jahili world of decadence and corruption in order to bring about "Dar-Al-Islam" (the world of Islam), characterized by Sharia law and a single ruling Caliphate between Spain and Indonesia. The source below is for the book which is the "Mein Kampf" for Al Queda and similar groups. It's only 160 pages long and is available in English.

Assuming all your suppositions are true, I'd say to stir up civil war in Iraq to cause more problems for the Americans.

History dictates that collaborators and treated more harshly when caught