When I am cruising, gear and rpm don't matter my turbo timer says 14.2 afr. then if i come up to another car and have to slow down, I let of the throttle slightly so it's just opening the throttle plate and my afr goes to 13.8 or lower and the check engine light comes on. After checking the code, I find it is an O2 sensor fault, but the o2 sensor is new and has been replaced several times.

 

bump

 

probably a fuel injector issue since you have larger injectors. The factory pulse width goes way out to get normal readings. The millisec readings probably go to low and the mil sets. If now managment is being used I rec lower cc injectors and raise the fuel pressure so it gives less fuel on lower throttle. IMO

 

what mangement are you using?