I was been told by the workshop that there was a code indicating that the cam shaft sensor having problem. it was reset by the workshop. No problem for the first two days after re-setting. The problem comes back again on the third day.
They just reset it and the problem came back within 2 days.
Have send my car to other workshop, found that the cam shaft sensor damaged, transmission gearbox also faulty, need to overhaul and change all the electrical parts, as recommended by the workshop.
It costs me about SGD$3k plus..... no choice, but really desperate to get the problems solve once and for all.
BTW, thank you for your advice Jeffrey.