OM606 turbo I assume

If you have a bad MAF you will get the P0100 fo MAF failure, and the P0400 for EGR issue (because it uses the air flow value via the MAF to determine if the EGR is working).

I would try replacing the MAF. Note the OE MAF is a couple hundred. But with a little sleuthing you can find the Bosch sensor online for much less. You will need the HF tamper proof bit kit to get it out.

You can try MAF cleaner but in my experience that is a fool’s errand.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech