My car is a Toyota Vitz 2007 and it has 80k KM on it. I usually drive short trips (about 5km) most of the time in a low traffic road. Car drives mostly fine in these short trips. But, if I drive for about 2 hours in a congested road with frequent stops, engine starts to hesitate when idle and even stall sometimes.
Hesitation is more apparent if I apply breaks suddenly and stopped. Also, when I step on the accelerator when engine hesitates, it doesn't respond correctly, no matter how much I press (it slowly accelerates).
If I enter a highway when the problem occurred, I can't feel any difference when I drive at higher speeds. Hesitation only occurs when driving in traffic.
Also, even in short trips, car sometimes idles very roughly (sudden heavy vibrations). But it doesn't hesitate or stall.
Also, in my morning drive to office (short trip), car idles smoothly. But in evening drive to home, idle is much rougher.
What I have done so far:
- Cleaned throttle body
- Replaced spark plugs
- Replaced ignition coils
- Replaced fuel filter
Can someone tell me what is wrong with my car?