Could be that or maybe a problem with the modded MAS. On the grand nationals you could pull one MAS screen, but if you pulled both, the turbulence would skew the readings.

Got a obd tester with reading capability? or Swap the stock MAS on the front of the TB TEMPORARILY(no air filter!) and see if you still get a lean code.

The engine can't draw more air due to intake design without forced induction, but, it can draw in more unmetered air through a leak, than the computer can compensate for.