Revisionist history seems to have struck you. Please read the 27 bullet points in the request for use of force that most all of congress approved. Just go read it. It's quick.
Just google "Authorization for Use of Military Force Against Iraq Resolution of 2002"
"...Whereas members of al Qaida, an organization bearing responsibility for attacks on the United States, its citizens, and interests, including the attacks that occurred on September 11, 2001, are known to be in Iraq...
Whereas Iraq continues to aid and harbor other international terrorist organizations, including organizations that threaten the lives and safety of United States citizens...
Whereas the United States is determined to prosecute the war on terrorism and Iraq's ongoing support for international terrorist groups combined with its development of weapons of mass destruction in direct violation of its obligations under the 1991 cease-fire and other United Nations Security Council resolutions make clear that it is in the national security interests of the United States and in furtherance of the war on terrorism that all relevant United Nations Security Council resolutions be enforced, including through the use of force if necessary;
Whereas Congress has taken steps to pursue vigorously the war on terrorism through the provision of authorities and funding requested by the President to take the necessary actions against international terrorists and terrorist organizations, including those nations, organizations, or persons who planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such persons or organizations;
Whereas the President and Congress are determined to continue to take all appropriate actions against international terrorists and terrorist organizations, including those nations, organizations, or persons who planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such persons or organizations;"
Are we reading the same resolution? The one I read accused Iraq of being a nation that harbored and aided al Qaida and other international organization and was developing WMDs for them. How'd that search for WMDs turn out?