Our Vios 1.3E M/T has developed this issue, while in stopped traffic, the car in neutral with the aircon on the car's RPM would occasionally drop to 300-400 RPM almost stalling.....
I don't know why this is happening.
There are no check engine or other warning lights showing up.
The car is only 21 mos. old, Casa-maintained (recent 25k checkup), not an ondoy victim
I tried using V-power or Xtreme97 (at different gas stations) to lessen the rough idling but the issue still persists.