Hi There

I have a Fiat Seicento Sporting 1.1 2001 model

For the past few months i have had an electrical intermitant fault.

I have changed everything from ECU ( i got another ECU but done the same , so replaced back with my own ), sensors, coils , bogi leads and fuel pump,
but prob still occurs.

Problem:

When i start up , then the car idles rough for about a few seconds , the
engine light stays , until i wait for it to disapear and idle smooth.
OR sometimes i have to REV up the car to get rid of the rough idle and
engine light to disapear.

In the mornings , it is the worst as the engine is so rough that it takes
longer to become smooth..

No when i drive, i can sometimes, but not so often feel a liitle jerg while
driving, but just say 3r gear going into fourth say a speed of 60 - 80
km's/phr
Then it goes away.

Had it on machine for diagnostics, but as you know, one prob just leads you
to the next, and then you tend to replace parts which is not neccessary.

Is this a common problem on this car or FIAT itself, can you help?