Car start problem

[jorizk]

Hello fellow Yaris owners,

I've had my Yaris for three years and a half now. Two days ago I got into the car. It was 5 pm, the weather was fairly warm, and I hadn't used the car since 11 am.

When I started the car, the rpm went on 1500 like it used to do, and in two seconds it dropped to 300~400, the car started to shake for a little bit like it was choking, and then the rpm went back on 1100 approx, but the needle was pulsing to ~1400 every half a second, and the pulsing stayed for a minute, even when the rpm dropped to 800. The car was on park all the time. When I put it on drive, I felt the pulse effect for the first 500 meters, when the gas pedal was slightly pressed, like it can't accelerate as it normally does and after that when it picked up speed everything disappeared. The car was behaving normally on the road, even when coming at full stops.

This thing happened to me three times before, but it's the first time the rpm drops like this. What do you think is the problem? I've changed the spark plugs and the air filter recently.

Thanks in advance:)