P1093: Fuel pressure low during power enhancement
P0087: Fuel rail pressure low
(these are off an LB7 list, but I don't think they changed much for the LLY)
So, what kind of tuner/programmer you using? This is an indication that you are probably using a big tune. It might be time for a lift pump if you want to continue using this tune. Another thing it could be, is a clogged fuel filter, but it could be a long shot if you just changed it. More information on your truck and a signature might help get more replies on that.
this happened to me when i had a clogged fuel filter and I accelerated really hard then immediatly let of the accellerator...needless to say I limped the truck home at 10k. A simple fuel filter change and problem solved