Google Rheingold ista/d software. Without that, you will have trouble doing anything on a diesel. Your issue could be as simple as a bad thermostat. If your engine never gets above 70 or so degrees c, your DPF may not regenerate and it could clog. A few 335d people have fixed clogged DPFs without removal. Search in the E90 diesel forum.
N57 / M57 Turbo Diesel Discussions - 335d - E90Post - BMW 3-Series (E90 E92) Forum