Avanza Engine Problem

[xda2jojo]

ISC bos, yong nilagyan mo ng red box, Idle Speed Control or Controller.
TB, Throttle Body, kung saan nakakabit ang ISC.
Ang MAF(mass air flow) sensor, yon ang nakatusok sa Air Cleaner "Box".
Pag solenoid na term, same as servo, a motor or coil driven device to pull or push, or to close or open a hole, yan ba yong nagtutulak or humuhila ng isang parts ng makina.
Iba ang sensor sa selonoid.

Sa erratic rpm, usually nasa TB parts ang probs nyan,
Could be the Idle Sensor and the ISC
Could be the Vacuum Lines, May solenoid dyan banda.
Could be the MAF or the oxygen sensor.
Worst thing...
Could be a Dirty or malfunctioning Injector or the spark plug.
Could be the fuel pump

Update as again bos kung ano na...