Ya,u r right that is me!being the rich spraying too rich guy.after the mechanic(another one)checked,the problem is probably due to my air flow sensor problematic.after some chi-chat,he suggest me to change the air flow sensor too 4g93,claimed more better.so i take this opputurnity to ask him about the price to convert to Dohc.he offered me Rm1300,at first but discount again to Rm1200.he said including all parts that need to change,eg:disributor,spark plug,plug cable,engine oil,oil filter...