A non linear MAF output could be the culprit or a small intake leak maybe. What do you think? Testing the MAF would require some way to blow into it. Perhaps it would be easier to just swap it out as a test. can you think of another sensor that could lead to this? TPS or temp? Ultimately, the ECU?
I must tell you; for us home/hobby mechanics these jobs turn out to be much more difficult than to the pros. I once observed an electronics tech work on a Gas Chromatograph that was malfunctioning. He came in will all the boards of the instrument. Started swaping them out till it worked. The techs at Z1 have access to a lot of spares that they swap as testing schemes.
