All eight at once seems really strange. I would pull the battery leads and let the computer reset and then see what code comes back.
2006 GMC LBZ/Allison 4x4 Crew Cab, White, Rancho Lift, 325 Yoko A/Ts on 20's, DSP5, ECM by Duramaxtuner.com, S&B CAI, 4 inch MBRP, Sulastics . . . and a carseat in the back.