It's not a potentiometer, it's just two microswitches in a potentiometer like enclosure. You should adjust it so, that it clicks when the throttle goes to idle or full. If you're somewhere in the middle, the ecu doesn't know where. S1/S2 does have a after-run fuel cut-off. You can clearly see it working if you rev to 4000rpm and suddenly let go of the accelerator. The revs drop really fast to about ~1800rpm where you can hear/feel the motor kicking back into action again. The fuel-cut is operated via the EMFCPA (Electro Magnetic Fuel Control Pressure Actuator).