You guys need to get rid of those tires and drive a little more lol I got 18.6 unloaded and 19.5 all hand calc still stock. Those tires are killing you!
All the 6.8.9 update for the '13s is enable high sulfur tuning for the C&C models, doesn't say much for the standard models, don't know if there was any modification of the actual tuning files.
I've never seen that with my '13. I give it hell every now and them also.
I am pretty sure I got a weak CP4 or lift pump from the factory, it's really tough to tell if it's the rail psi while using the minimaxx gauge. I don't think it's the lift pump tho, I mean the CP4 on a duramax doesn't even have a lift pump, and it runs just fine. So I am thinking it has to be dropping rail psi. I guess an upgraded CP4 or the addition of a CP3 is needed. Might as well do a turbo and trans too while I am at it!
My truck threw the same code while towing an enclosed trailer this weekend on performance. I was talking to Rudy when I was in Bowling Green for Ts and he said that his truck would do the same thing. So I really think it is in the tuning.