I had an '02 Z-71 that i recently sold that had similar problems. I had to change the fuel pump 3 times before i got a good one, so don't think it can't be the same problem. Also you should try and take it to a mechanic and get a fuel pressure reading. I think the pressure should be around 55 psi anything less will trigger the codes. My truck was sending the same codes... lean bank 1 and 2. So before you drop any money get a PSI reading, it shouldn't take more than 5 min.
P.S. The 55 psi is just a guess. The mech. should have a book with all the numbers for ya.
Good luck, my truck gave me hell.