Ok so the car in question is a 2005 Audi A4 2.0 TDI 140 (BLB Engine)

I sold the car and on the way back home the lad complained of it bunnyhopping, so he took it to a garage they fitted a new maf. Next day same issue just getting worse, so I have swapped back for now. Just replaced the EGR valve with a brand new one(The old one had snapped, flap no longer connected to rod). Still the same issue. Now this is where it gets complicated!

With the EGR plugged in, the car idles rough, cuts out, plooms of black smoke out of the back, barely drivable. (all of the typical EGR symtoms)

With it unplugged the car drives fine. Also with the EGR plugged in and the MAF unplugged it drives fine.

Now the confusing part, regardless whats plugged in or not, on vagcom the Exhaust Gas Recirc (actual) and Mass Air Flow (Actual) are identical values. (With the EGR unplugged the values stay fixed at 550mg/str if I remember correctly. With it plugged in it is identical to the MAF (actual) which is obviously a long way off what EGR (spec) states which causes it to run the way it does. I assume these values being identical aren't normal and whats causing the car to run the way it does, what could the problem be? Spent all day trying absolutely everything I can think of! Any help or suggestions would be greatly appreciated!

As far as I know the car hasn't been remapped so it should be running the standard map and was running perfectly fine a few days ago.

Big intake leak, bad maf, bad/shorted maf wiring, wrong maf.

should be trivial to debug.

have you logged maf voltage yet?

overboost is usually due to bad tune or torn wg lines, not map related.

log block  115 this is requested boost vs actual