Subaru added fuel treasure throttle, and the idle speed was unstable.

What you want to ask is why Subaru's idling with fuel treasure throttle is unstable. According to the query, Pacific Auto Network shows:

1, some parts of Subaru car are caused by too much carbon deposit. When idling, the car body shakes, mostly because the engine, throttle and nozzle have too much carbon deposit, and the car will shake.

2, Subaru car ignition system problems, such as car spark plug gap is too large or too small, there will be jitter, or spark plug carbon deposition is more.