I've been having a few issues with my E320cdi with V6 OM642 lately. It started with a loss of power and slow to build up revs, but I could drive round it by using manual gear change and keeping revs around 2500. This felt as if turbo not working and confirmed by watching actuator, but if I restarted engine the actuator would test ok. At this point I was getting code 2510-091 check component Y77/1 After a few more journeys I then also had code 2616-002 check component B60(exhaust back pressure sensor). Control variation - exhaust back pressure is too high When testing either of these components via STAR, both checked out ok. I reset codes and drove for a few days. It then drove better once warm, but when cold it wouldn't rev over 1500rpm. I then got codes 2513-001 check component M55 (inlet port shutoff motor) positioner signals fault and 2510-001 as above I checked inlet port shutoff motor and this tested as not ok on STAR. From info on here I found it was possible to bypass inlet shutoff with a 4.7kohm resistor. I did this and on STAR it now tests as OK, but I still have the same issue of the engine not revving over 1500 rpm when cold. Also the only code I am now getting is 2616-002 check component B60(exhaust back pressure sensor). Control variation - exhaust back pressure is too high. It also seems to be running rich, both by smell and very sooty exhausts. I'm also pretty sure I do not have a dpf fitted as I don't have code SA code 474, so that can't be giving back pressure. So, my question is, is this likely to be the turbo as this was the first code I had, or the swirl flaps as I've bypassed them or the just the back pressure sensor ( which checks ok on STAR ), or a combination. Any help appreciated before I spend money replacing parts.