duramax overheating

I have the 05 as well and have experienced heating issues. I know that this sounds super obvious, but all of my heating issues are related to up hill towing on hot days with a load. My solution has been to plan ahead and try NOT to drive when this scenario is present. When crossing the major mountain passes I make it in the mornings and evenings with no problems in the summer time.

I tried a different intake, but didn't noticed any real improvement when heat, hill and load (towning) were present.... returned it for $$.