OMG. I now completely get why people block off the EGR valve. I'll have to post some pics for you to believe what I'm seeing. A-maz-ing. The base of the inlet trumpets are so clogged I'd say that the diameter of the air flow duct is only about 10mm instead of 30. Who knows how bad the back of the inlet valves are. I know that the inlet ducts (leading to the inlet valves) are really bady clogged with soot. Hard gritty material it is. I thought that it may have something to do with the blow-by gas