I have the same problem, I have a 2002 bmw 330d auto that is lumpy when cold and making a pinking noise when accelerating it is also a lot harder on the diesel than it was before, there's no fault codes showing up and the guy working on it at the minute is baffled. A few weeks ago it put on the dde light and went into limp mode, but the guy that has it at the minute is going to put some injected cleaner in it and see what happens.