when you add any load at idle the idle air motor opens to maintain the idle speed - this increases the airflow at the
MAF which = slightly higher
MAF output voltage.
you only have a .02 of a volt change anyway.......
Have you scaled the
MAF airflow curve correctly?
Have you done the 30 minute PFC idle learn with the new
MAF in place?
Have you watched the map tracer in FC-edit to see what fuel cell it is dropping into when the electrical load is applied at idle?
I'd say you have an incorrectly mapped cell, check the cells around where the pfc is sitting at idle with no load - apply the load & see which cells it's floating between (it should step down a cell or 2 on the load axis) change the fuel correction for this cell and it's neighbors to maintain your idle AFR's - these cells won't effect anything else in your map.
P.S I run my idle in the 16-17:1 range and 15-16:1 at cruise (14:7 at transition to boost (0 psi) and 11.5 at peak torque/boost.