sc400baba92

I bought my 1992 SC400 in 2002 with 175,000 miles on it and currently it has 215,000. I am the third owner of the car. Since buying it, I've changed the radiator, ignition coil, alternator, windshield and have given it a tune up. The past two years I have had a problem with what appears to be the mass air flow meter. When I start my car, especially when it's hot or has been sitting in the sun, it doesn't always stay on. Sometimes applying gas immediately after ignition will trigger something that makes it stay on, but usually it's hit or miss. Trying to buy an air flow meter new from either a part distributor or a dealership will cost me anywhere from $900 to $1,100 dollars. I tried replacing the part with one from a junkyard, but the problem was still there; Either cause the part was as bad as mine or that the mass air sensor isn't the actual problem. Has anyone heard of this problem before? What's my best option here?