A colleague had a DPF remove done professionally around 2 years ago(garage, website, reputation), and for the last 18 months he's been complaining that his car is broke. He doesn't seem to see the connection. (Although I may be wrong) but heres the story

He can be driving quite happily, but after a time on the motorway, or maybe towing a small van, the power is just gone, wont rev very high and is generally unsafe.
If he pulls over and lets it cool down for 5 minutes or more he can then re start it with a dense cloud of smoke and it works fine again for a while.

Does this sound like a messed up dpf delete? and it hits a temperature limit or something. I've never been in the car to experience it (limp mode etc), this is just going on what he's saying.