I have a 2005 LLY with EFI live and I have been having some boost issues so I wanted to flash it back to stock to see if it's the tune causing the issue. There are 0 codes being set, not even in history. I used the tech2 to check for codes since I am a mechanic at a GM dealer. Programming through TIS fails every time. Doing both regarding programming and replace and reprogram. I've got remote start and aftermarket stereo. I've tried pulling the abs, info, amp and radio fuses and removed the stereo and remote start. Still doesn't reprogram. We had another truck in the shop that was an 05 LLY and I put my ECM into that truck to try and program it since it was completely stock and it still failed. EFI can be reflashed but stock can't. Anyone have some suggestions? I've tried programming using the MDI, and tech2 legacy pass through and just with the tech2.