Why are we still in Iraq?

In 2002 we were told we needed to invade Iraq because Saddam Hussein was making weapons of m destruction, and he had connections to Al Queada so in 2003 we captured him, and he was executed, and Bush announced on national TV the mission was complete. So it's almost 7 years after we removed Saddam Hussein from power, and got rid of the weapons of m destruction that were never there. So why are we still in Iraq? Can't the Iraqi government handle their own problems yet?