I am relatively new to the TDR and what a great place for information. That why I am making this post for your information and help. I have a friend that has a 94 CTD 3500 dually with over 300,000 miles and no modifications. His problem is that while driving without a load and even worse with a load is that the truck will start puffing alot of white smoke. It does not do this all the time. The motor does not seem to cough or sputter but acts the same as one that has hit the governor or the rev limiter if that is correct term. It just loses power puffs white smoke for just a little bit then will start running fine and does not puff white smoke. The fuel filter has been replaced and it continues to do this, also the air filter is clean. Any information would be greatly appreciated.