Response, Gain, Idle, Option Out (not normally used)
It's best to just leave everything at zero and use a piggy-back fuel controller such as a SAFC. The VPC has limited adjustability.
IIRC Response will add or subtract fuel on initial throttle opening only. Gain will add or subtract fuel across the board and Idle is just that. Adds or subtracts fuel only at Idle. Option out is for an FCON which is not available for a U.S. spec Supra.
I hace the S-AFC, but the way I have it set-up, I have no control on 4500 RPM and 5000 RPM and I'm running way rich at those points. I want to lean it out a bit and adjust a bit everywhere else since I can. Just want to smooth out the air/fuel a little more. Thanks again.