I have a 2010 LMM Duramax. When the truck is below 180 +- deg. It idles rough and has one injector pressure (#8) at about 7mm. It smokes really bad as well. Once it’s warm it runs great. New injectors. And I took the one injector (8)with high rate and switched it with another (6) and problem stayed in original (8)cylinder. New ECM, new GPCM , new map sensor . EFI Live , dpf delete, EGR is still on just inactive. Somebody please help !