i am not sure about wira, but sentra has something called IACV or AAC, Idle Air Control Valve. Carbon can be deposited here and becomes clogged, air intake will not smooth and idling becomes not stable and potentially engine stall. See if wira has this gadget and take it out, use WD40 to clean it.
Another area to look at (my sentra) is the collant temperature sensor. If this thing not working properly, minor will be unstable rpm idiling, worst case engine will stall and you will not able to start the engine within
My problem is when the engine stall, i cannot start the engine. Only way is to floor it and engine started very loud and rough, rpm still not stable for first 2mins, after that everything ok and back to normal. By right when this sensor has problem, it should throw a code to ECU to record as log, it didn't.
hope this help, check the IACV first.