Ok ive got a 2006 gmc old body 1500.HAs os 12606807 and there is no custom os for this op system.So i jumped down a year to run a 12592618 were there is a 0521003 2 or 3 bar deal...Problem is no matter what i do it goes into reduced power mode and gives me a list of throttle body codes..I really dont want to do a hack maff 1bar tune on this truck...Any help would be great.