The resistance should fall from infinite resistance (flap closed) to 0 Ohms (flap slightly open). If no transition from infinity to zero, replace air flow meter.
Using the bypass air screw in the air flow meter to adjust idle mixture, set the CO to 1.5-2.5% with the engine at normal operating temperature.
With the engine at normal operating temperature, set the idle speed with the bypass screw on the throttle housing.