Mine is currently set to 15,500, 8192 and 300F as the minimum.

 

Also, what size is the pipe for the MAF? smaller tubing increases velocity and thus cools the maf wire quicker.

 

I believe its 3" if I'm not mistaken?

 

Seeing as how it almost reaches an asymptote in the graph, it could be a symptom of contact resistance. The MAF in the software reads as a frequency, but that value is converted from current. If there is excess contact resistance at high current, it stands to reason that the MAF could appear maxed out before it actually is. Do a thorough cleaning of the contacts on the plugs. Don't just use some cleaner spray, get in there with a pick or something and scrape off any crud that might be on the pins. As for the rich to lean transition, that could be a result of other things in calibration...it does look to lean out right as it hits the transition to filtered MAF. Or, it could be nonuniform flow through the MAF. That happens all the time, especially with card style MAF sensors and a turbo upstream...