Do you test when running or with ignition off

 

What's you're issue?

if odd things, unplug it, preset values are used...if it runs better, then maybe MAF of a flakey MAF relay...i/e air going in confusing the incoming air reading.
I don't recall, but without a scan toon you can see what the MAF is reporting, what I can't recall is the numbers you should see on the scan tool. All my babbling aside, unless you see something visually wrong looking through the screens, I don't know of a way to test it with with engine off.

 

A running test can be perfomed with a voltmeter.