About 2 years ago, while my dad was driving my car, the car jerked a few times then it stopped. He was driving in the highway that time at 110-140km/h. The fault was because the temperature meter was not working. So, i guess it overheated and all.

After repaired, the car was very rough n underpowered. The pistons also made so much of noise.

Anyway, the car has been repaired now. However, the pistons still make a slight noise if the car if driven with rpm lesser than 2k. Any suggestion on...