Billy Bob

My 1995 nissan 200sx mass air flow sensor seems to be running under specified voltage. At idle the book says it is supposed to be 1.3 to 1.7 volts at idle and 4.0 volts at 4,000 rpm. When I tested the voltage, I was only getting 0.2 at idle without much change at 4,000 rpm. I have noticed over about the past 3 or 4 months that the car's power on hills has decreased and the car needs to downshift on hills in which i used to go up without downshifting at the same speed. I was wondering if the airflow sensor was bad or not since the sensor is going to cost me about $200.