Great read. I'm having similiar problems but at higher revs / under heavier load. This thread helps to try and identify some of the areas of possible concern. My EGR valuve was very oily like the OP's. I replaced this along with the elbow intercooler pipe in the back of it, plus the main front intercooler pipe as that was perished and startting to split (but not right through yet). Also replaced most vacuum hoses, but slil have an overboost issue resulting in limp mode. I'm not sure if I should have flushed the intercooler, or if this is a sign the turbo seals are going. I also don't know if vacuum line to the EGR actuator is supposed to hold vacuum at idle, as it currently does not. If I operate the actuator rod by hand, the engine starts to stall. I therfore think the internal flap is supposed to be open at idle / lower revs and then clsed later in the rev range, but how do I tell? And how do I know if the solenoid telling it to apply cvacuum is actually working? I currently don't know if these all count to the same problem or are misleading in the overboost issue. Any ideas chaps?