[DeliciousTuning]

Originally Posted by Mr_Eyo

I have an AT with the Edelbrock kit and v25 tune for flex fuel and am having a rough idle. Sometimes sitting at a light, ignition advance timing is -2.5 deg. STFT is high, like +25%. Load is a little higher than normal. Vacuum sometimes is only -7psi vs the normal -10psi, so I imagine the bypass valve actuator is partially open, flooding the cylinders with compressed air and the ECU is pulling timing. If that sounds plausible, where could I be having vacuum issues?

Yes, this sound like you have a vacuum leak and probably at the bypass valve.