It is very important to have the air flow meter set up properly. If it is out of adjustment you will never have the proper mixture throughout the rpm range, you will have lean and/or rich spots throughout the operating range. Inside the air flow meter there is a leaf spring that serves as a stop for the sensor plate. This spring is adjustable by moving a steel pin up or down. This pin is usually flush with the top surface of the air flow meter located directly under the fuel delivery line fitting on the fuel distributor. To move the senor plate down, drive the pin down with a small drift. To move the sensor plate up disassemble the airflow meter and drive the pin up from the bottom. The result you are trying to get is the edge of the sensor plate should rest at the narrowest part of the cone shaped opening at the point farthest from the fuel distributor both with and without fuel pressure.