From what I read in your thread is that the MAF should drop about .5 volts when the ERG opens. I am still wondering what the system looks for to trigger the wastegate solenoid code (P0243)
I am going to try swapping out the transducers to see what happens.
In the past I have always tried to have two vehicles that were the same just for the purpose of troubleshooting. At one time all three of my kids had 4 cylinder Mustangs. It was easy to figure out what was bad by swapping parts or comparing readings.
Now I just need to convince the wife that having a couple more E300s could save us money.