Larry
did this become a bigger problem after the induction work?
can you post a log of IAT and boost for your typical drive? If you haven't dampened IAT swings, this is a big part of the issue.
also, if you can somehow log COT, compressor output temp, that may be a big part of the story.
BTW, I am working on producing a fan pulley that makes more sense. Google search "fan drive ratio" for LLY duramax, and you may see what I am talking about. I decided in 05 that the LLY fan was overdriven, and may finally get around to fixing it. This will preserve flow while reducing noise and parasitic loss.