I wouldn't worry too much about the carbon buildup in the throttle body. Give it another week and it will be the same again. Unless the carbon is so thick its causing problems with the throttle sticking, no worries. The EGR doing what it does best causes this, unless you get rid of it, you will have the same problem as the rest of us. Clean it and put it back on.

The rest of the problem... I have no idea.

sorry, but good luck