I got a 2003 Fiesta MK6 1.4 Zetec Petrol.

First it seemed too underpowered and stuttering when it's in low revs / full throttle so i gave it to a local garage and he found that the CAT was broken.

So I replaced with a new one ( which cost me a lot) and the underpower problem is solved...but not the stuttering.

The car even has some slight shaking when idle, not frequently but you can feel it.

Any help will be appreciated.

Could be the HT Leads breaking down under load, which is common. Its worth changing these anyway, at the same time, do the plugs.

Could be the HT Leads breaking down under load, which is common. Its worth changing these anyway, at the same time, do the plugs.

Should I stop driving the car until I give it to a garage? coz I am afraid the CAT will be damaged somehow...I cant afford to buy a new CAT again

You should be ok using it for a short while. Alternatively you could pop to Halfords and by the bits yourself. Should only take half an hour to do.

You should be ok using it for a short while. Alternatively you could pop to Halfords and by the bits yourself. Should only take half an hour to do.

I would like to do that but since I am a overseas student here I dun own any tools to do it myself ....