I may be wrong but as I understand it, the MAF only effects the EGR operation and doesn't effect fueling (unlike a gas engine EFI system). In this case, it may be setting codes but the codes are what puts the computer in limp mode, not the bad MAF.

The modulator for the wastegate is, as you say, the one behind the right hand headlight. There are 2 lines coming out of the top, one is the vacuum supply and the other goes to the wastegate. I was suggesting removing both of these top lines and connecting them together to keep the computer from limiting boost.

This will tell you a couple things. One, if the car doesn't respond and accelerate normally after bypassing the modulator, I'd next look at the MAP sensor (the one with a single vacuum line and a 3 wire electrical connector) on the left side "false" firewall next to the intake.

When you get to that stage, I can tell you how to test it with your MityVac.

I just want to take it one step at a time for organized troubleshooting. First just verify vacuum at the modulator and the wastegate.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250