My 6.9 idi blew white smoke until warm and under light acceleration. Put some fuel cleaner in it and clean the lines mine ended up being a clogged return line. I just rebuilt the injectors and put all new return lines on. Cant tell if it really fixed my problem though being as i just blew the turbo. Got a spare 7.3 idi going in this weekend.
what kind of cleaner did you use ?