I am having the same issue as well in a 5.3 silverado. OP stated a few posts above that he found multiple vacuum leaks causing the issue. about to go check the same on my and will update if I find anything.
Have you figured out this issue yet? struggling with the same thing on my truck. injector balance is way off bank to bank. no codes though. Although I do have a pretty bad misfire at idle. completely clears up as soon as I hardly tap the pedal.