So about last week Wednesday my car (2000 GT) started to feel like it was misfiring or something. Car has 153,000miles so its probably time for something to be replaced. The engine light did not come on right away and I was not sure what was going on. Eventually the light came on (first time in the 2+ years of owning the car) so I took in to an auto parts store and it gave codes P0171 for System Too Lean (Bank 1) and P0102 Mass Air Flow Low Circut Input. I pulled out the MAF and cleaned it again and put it back in. Still have the problem. Someone told me its possible that I have a vac leak so I sprayed ether stuff all around and engine did not jump so I figured it was not that. O2 sensor is the only thing I can really think of that may be causing the problem because the MAF looks perfectly fine. I thought that there was a test that you could do by unplugging the O2 and seeing how it ran or something but I am not sure. Any help is appriciated. I've been pretty busy with school and stuff so I might not be on here much to give feedback but we will see.