is the throtlle potentiometer failure a common problem on suzuki liana? poor idle/ running on light throttle.

Believe it or not, this is a common problem for a lot of cars out there that use such a device for electronic throttle location reporting. Most sensors/Potentiometers are under $60.00 and a good place to start.

l know on other Suzukis that the Throttle Position Sensor (TPS) can and will go out of calibration from time to time. Frequently it will be accompanied by a Check Engine light. It is a simple fix with a multimeter, a screwdriver and a feeler gauge. Consult a factory service manual for info on how to do this.