Id take another look at that TGV motor. Its possible thats all it is. I once re installed mine incorrectly which cause the car to chock and jerk above 3k rpm. Same might be true for you but opposite. I dont know much about the ECU and Fuel System mapping so i cant help out with what the other guys are saying. Im not sure but if youve got a CEL wouldnt your car go into to limp mode and revert to a safe map that doesnt compensate for o2? Maybe someone could shine some light on that subject cuz i honestly dont know im just assuming. Good Luck!