Mazda 626 idle high problem
 

I have a 99 mazda 626 4 cylinder and the idle is a little messed up. Thought it may be the IAC adjusted the idle screw while it was running and I can stall out the car by adjusting it down. Shouldn't the IAC let the air bypass the throttle? Instead of stalling? The check engine light says Mass or volume air flow circuit low input what do I need to buy to get this check engine light to turn off.