Just a little somthing.. It took 1 month for all the air bubbles to leave the air lines in my car. It looks like it is a self purging system but I swear I watched the same air bubbles circulate around the IP. My wife also noticed that the car ran better above 1/2 tank.
I to had simular problems (white smoke). In the end I replaced the fuel lines & cut off solinoid, came up with the diesel purge proceedure, and started using redline 85 plus diesel fuel enhancer. It took a month for the car to really start to run good. The car now runs so good it sounds like a 2004 cdi.
Other factors could be the fuel at the pump and warmer weather but I will know next winter. We have had some cold days recently but the car still purrrrs.