MAF Sensor Tables
There are four tables for the MAF, which split up its total frequency->airflow grid.
First, find the airflow reading for your idle in your logs. Then, find the closest value(s) in the MAF sensor tables; you will sometimes have to alter two cells to affect one airflow range.
To richen your fuel mixture (BLMs > 128), increase the value(s) you found as mentioned above.
To lean the fuel mixture (BLMs < 128), simply decrease the appropriate MAF cells as mentioned above.
These values are also efficiently modified using percentages (%), or multiplying the values (1.xx to richen, 0.xx to lean). Start with 1% (1.01/0.99) changes for every 2 BLMs off; so, a BLM of 118 would require a 5% decrease (128 - 118 = 10 / 2 = 5), or multiplying the MAF airflow value(s) by 0.95. Again, trial and error will be needed to see if you have overshot a BLM of 128 with your changes.