I own a 1998 Punto 60SX (8 valve engine) which has done 56,000 miles.  It
has had regular servicing and until this week has run faultlessly.

It has now developed a slight problem and I don't know what to check.

When starting from cold it starts first touch, but runs roughly for about 20
or 30 seconds, as though misfiring.  After this it runs fine.

My thoughts are

* change the plugs - they are about due (20,000 miles since last changed)

* clean HT leads & check they are secure

* Perhaps disconnect & reconnect battery to "wipe" ECU memory - could it
have become corrupt?

Beyond this I'm stumped.  Most fault finding information I have seen refers
to rough idling or rough running, but mine runs rough if idling or pulling
away then idles and runs OK after a short time.

I'd be very grateful if anyone can suggest a likely cause - especially if
it's cheap to fix :-)

Cheers

Rob