Follow up - Fuel system was losing prime. Re built fuel filter housing and used the GM "upper engine cleaner" while I was at it. So far so good.
As a side note, truck seems to be getting better fuel economy now. Not to start a major debate here, just posting my observations...
Thank you all for your help!
05 4x4 ex cab sb LT - LLY - allison - line X - TruXport - Lund Interceptor - Xtreme catch all mats - BFG AT 285-70-17-H2's - Firestone Air Bags - FloPro 4" exhaust - Magnaflow downpipe