David, where are you performing the smoke test?
Remove the maf and test at the main pipe to turbo, this will confirm the whole intake curcuit, see what pressure and flow you get there, leave ignition on.

It's clear there is not enough flow and is either restricted or bled off, egr operating at 100% dc will give you your reading of 18kg/h at idle, so double check it's closing fully, put a plate between to confirm, but skoke testing at the maf will show the same.

Also, have you personally loaded the latest software and not just checked it's the latest, just incase someone has done a bad egr/dpf removal?

Also, have a look in programming, some newer stuff especially dpf models require adation resets for egr and maf and a bunch of other stuff.

Appologies in advance if you've already done this.