Car has hks fcon and vpc plus more but those should be the two to worry about. I have checked and verified all the vacuum lines are correctly routed and i have no leaks. I am in the process of fixing a code 51 but am wondering will that cause the car to idle rough and almost stall when first pressing on the gas pedal? Thats my only code aswell. I know the vpc is working because if i adjust the idle knob too rich or lean the car will stall. Also timing is dead on.