my 81 240d was running terribly on cold starts even in the fall ... lots of skipping, smoking and very sluggish when getting under way. I knew it was time for three procedures. I adjusted valves, removed the injectors for a thorough cleaning, removed the gp and tested each one. Now even in the low temps we've been having in the n'east it starts much easier runs smooth and very little smoke. within a month of this maintenence, new fuel filters and air cleaner were installed. I must have picked up a bad tank of diesel, my primary fuel filter was clogged and starving the engine! never had that happen before and almost got me stuck. good luck, mark