I have an 07 2500hd with an issue that I just can't figure out. It only acts up when your towing or giving it some "gas". it will have a power surge right before it goes to shift and after it shifts it will blow black smoke out the exhaust. I was thinking in the direction of a vane sensor but most people I have talked to said that will throw a code. The truck has no codes stored or anything. Have put new air filter, fuel filter, and air cleaner in with no change. And I also forgot to mention it has this odd whining sound as well I don't think it is the turbo because you can hear that spool as well. Don't know if it's all related or not