on a el v8 motor, what voltages does the plug suppose to have across what pins. also, is it possible to open or clean the air flow sensor?

Pin A is 12v, Pin B is ground, Pin C is sensor return voltage (0-5v) and Pin D is 5v. To clean the sensor, just remove the electronics from the MAF body, there are 4 security torx screws which hold it on. When you remove it you will see the sensor wires on the back, carefully clean them with electrical contact cleaner which is available from d**k smiths.