wat does the mass airflow sensor actually do.....is it important?does it need to be ther?

It is an integral part of the engine. It tells the engine how much air is coming into the engine. It can not be removed! I believe that MAF sensors are heated element sensors and, by the cooling effect of the air, they produce a voltage drop across the sensing elements. They are ECU (engine control unit) is calibrated to the MAF sensor in its original configuration (ie. with MAF screen and cross-sectional area of the MAF assembly - 2 aluminum peices and the sensor itself). Removing the screen and/or porting the aluminum peices can cause incorrect readings to be sent to the ECU and may cause a lean condition in the engine. It mostlikely will throw a code as well.

Do you have a bad MAF? Or are you just trying to learn? Just wondering what prompted the questions?

just trying to learn