I was getting trouble codes 1174 and 1171, too lean banks 1 and 2. I figured it had to be something both sides have in common.
Someone said they thought it was a vacuum leak. I changed all the small tubes and vacuum checked all of it. I started to l think the idle control valve might be the problem so I bought a water valve from Home Depot and installed it between the Control Valve and the intake manifold. Trouble codes ate gone and the idle is smoother. How do I know if it is the Idle Control Valve or something controlling the Valve?