I had same problem and others told me that it is the gasket. Uuh but it wasn´t. I Think the Ecu has wrong values now. I had to reset tree times before it started to work properly. Reset ecu with Techstream or take a battery away for a night. After that the ecu will learn new values. For example I removed DPF particulate filter (clearing out) and install dpf emulator. Then my engine put lot of white smoke when the motor gets warm :D :D :D Other drivers was quite happy I think. If that battery disconnecting won´t help then you need to do it with computer. Hope this help you.
Here is a video link to my white smoke after deleting dpf and without reseting ecu-> https://drive.google.com/file/d/0B8kX0wl1NVy2WnZvUnJpeGtScTg/view?usp=sharing
btw: and the power is back now and consumption is about 5-6liter per 100km. Sometimes even under 5 liter. Veeery happy now. I was fighting about 6 month with my car.... no help by lexus. They like to sell only new and very expensive spare parts realizing that the problem is somewhere else like euro5 law and new diesels requirement (EGR+DPF=killing the engine)
