Erratic Idle "94 E320
 

My car is idling errtically form 550 to about 1100 rpm when in park
position only. When I checked the diagnostic module socket and pressed on the button, the led indicator gives a trouble code of 10 flashes which equated to a defective Mass air flow sensor. I checked other components such as OVP relay fuse (not blown), EGR valve (cleaned the carbon inside metal the pipe), replaced air filter and traced the connections to Air flow sensor. I disconnected one of the vacuum in the EGR hose and checked for vacuum. The result was good. I suspect the Mass air flow sensor is defective. Could someone tell me how to check this sensor? What is the reference voltage and the ohmic values of the sensor? I have schematic diagram for the air flow sensor and I want to know what are the values at each terminals. This part is expensive and I want to be sure that this is really the defective part.

Please help me locate the problem.

Thanks,
Fred