About a month ago exhaust brake quit working then lost power. Got 2BAC code and a permanent turbo code. So I replaced turbo and cleaned out the exhaust which wasn't even dirty. Truck ran good for about 10,000 miles and now the exact same thing has happened again except no turbo code. I have half power and a full load. What and why is this happening. The truck has about 200k on it. I have over 800K on my 08 and still have the original turbo. Any thoughts appreciated.