Please can you people help me out. After I bought a new Toyota Etios 2014, about 6 months, it started jerking (going faster and slower) without me using the excellerator. Then all of a sudden it started revving up. I can drive about 1km after starting the car, trying to stop at a stop st or robot and it will rev up to about 2000 - 3000, and this is when I have my foot on the brake. Even if i drive downhill, freeing, not using the excellerator, it revs up to about 1500. I took it for all services, complaing about the problem, but was told I can't drive and that it's normal. I then wrote to Toyota SA, who asked whether I have a problem to start the car, which is no and their conclusion was that it is the battery. I tend to differ and please help me out on your opinion. My opinion is as follows:

1. It could be a faulty airflow meter or being dirty

2. It could be a damaged or loose pipe on airflow meter

3. It could be a faulty brake booster or pipe from the manifold, as this happens when I use the brake.

4. It could be that the brake booster has an air leak cause it demands more vacuum when there is a leak.

5. It could be the diaphragm on the brake booster may have a problem, cause once again when I use the brake it's rev up

6. It could be the cold start which is faulty

7. IT COULD DEFINITELY NOT BE THE BATTERY, A BATTERY IS ONLY THERE TO GIVE POWER TO THE ENGINE TO TURN