This P0299 code has been driving me nuts!!
After checking CAC (repaired leaks), Pressure tested the hoses, removed the EGR, ACV and associated piping, Installed Weeks Intake elbow kit, Adjusted the GDE tune this code kept coming back. I could do an Italian Tune Up and after the third run the code would not reappear and engine would run great. Then after cooling down and starting up the code would reappear and run like crap. Black smoke, no power, and limp mode....This got me thinking about that darn Catalytic soot catcher. Sure as hell it was clogged up and preventing the turbo from doing its thing. I removed the 2 bolts connecting the Cat to the muffler and cleaned it with a hammer drill, thin wall pipe and a shop vac. Clean as a whistle now. Buttoned everything back together and a huge cloud of black soot exited on start-up and I could feel the engine breathing much easier. At last P0299 solved....
... 
This should be added to the check list for P0299 trouble shooting guide because there is no cel code for a clogged up Cat!
Cheers.......
