[That Guy]

the middle class an wealthy have mainly already fled iraq, the baath party was completely disolved (which was a terrible mistake, since that killed ALL the operational knowledge of the country), the afgan poppy farmers present a challenge to manage, since they can't make money or build the economy of afghanistan without, you know, making poppy (and they're a sizable chunk of the population).

america has only had two extremely successful nation building efforts in many many attempts. we oversaw the infrastructure construction in the phillipines a long time ago, and slightly more recently, the reuilding of japan after WWII.
both countries had very supportive populations that accepted the help.

in iraq, it's closer to some african nations in that there's no real national unity, only ethnic unity (kurd/shite/sunni), and even within that there are divisions in religion extremism, various anarchists groups, iranian involvement, etc.

the only real quick way to solve it is to divide the country and let them self rule and HOPE beyond hope that doesn't devolve into a territorial pissing match between those factions and neighboring countries... which it will.

there's no real good answer beside turning it into a really restrictive police state, which, in and of itself, it's a pretty bad solution.

the local population has to support the effort, but they've been taught their whole lives that america is bad and have a massive influx of negative views from middle eastern TV stations. there's also no real national unifying figure to help either.