Remember that air is going to also take the path of least resistance.  From the pictures, it would seem that you have more inlet than ways for the air to move past (aka the baffles).  You must always have more exhaust than intake to achieve proper airflow.  I'm simply suggesting that it looks like you have a wall around the motor.  When you try to force more air in than the baffles can move, the air will go around the inlets and the airplane instead of through.  I'm concerned that your baffling system is creating some headaches for you more than ducting air especially if it is true that the motor you are using does not have a built-in fan.