I have a 98 k1500. Ever since my mechanic changed my pressure regulator due to long crank I've have an issue with bank 1&2 too lean popping up on my codes. I've went through everything. The biggest issue is on startup if you put it in gear it runs like crap no power and like it sucks too much air. We have changed all the upper and lower intake gaskets. My injectors are not leaking. I've changed plugs, fuel filter and pump,o2 sensors, even did cap and rotor for giggles. Once my truck runs for a minute or two or warms a little it runs great! Im at a loss here and it's causing me to get 9-10 miles per gallon! Any suggestions would be amazing!!!

 

I also was having all kinds of issues with my '02 5.7 I would occasionally get those codes as well. It would stumble from a stop until it warmed up and power was way down as was mileage. It seems like I tried everything to fix it. One quart of Marvel Mystery Oil into the oil and 50 miles later all was well. Power and mileage back to normal.