black smoke and lumpy when cold.

[Polyphase]

First thing I'd be doing is going back to whoever re-mapped it.

[Polyphase]

Try process of elimination, take the box off first and see if that stops the smoking. Looks like you're looking for the codes to be read to sort out the judder.

[Lance]

Shouldn't be getting smoke - that would suggest that the DPF has been removed. The low mpg could be the car trying to regen the DPF. Lumpy running could be poor fuel delivery, probably made worse by having the box on.



BTW, on terminology, a box is not a remap.