2003 2500hd 6.0 odd vacuum leak issue

[Bladeboy1998]

Long term fuel trim on bank 2 shows full lean (so it's enriching fuel mixture). I thonk uou us are right, the smoke test results are normal, thats not an issue. Now that I singled that out, I need to figure out why it's full lean on bank 2, I've already done intake gaskets, tested them multiple times and they don't leak, injector o rings don't leak, I can't find any vacuum leaks. This seems like a simple issue.

I will also add, there is a noise under the intake manifold, it's not a knock, it sounds like it could be lifters though. Could my issue be the dreaded lifter issue? I dont know if they cause a misfire or not.