I have a 2004 1.3 Getz that has done 32,000 miles.
When started from cold and driving off it hesitates on acceleration for about the first 1/2 a mile or so then as it warms up the fault goes away and it drives normally.
I hooked up my laptop to the OBD port one morning wu=hile the engine was cold..

There were no fault codes so I thought I would look at some data instead.

Here's what I found:
I sat in the car and the car's display said it was 46F outside = 7.7 C.
My OBD software was saying the car's coolant was 8C and the intake air was 7C.
I then started the engine.
The pre cat lambda voltage started off at 0.2volts then steadily dropped down to 0.03volts.
After about 30 seconds or so the voltage started acting more normally and I was getting good cross counts.
After a few minutes idling the coolant was reading 77C and the intake air 22C.
It would appear the temp sensors are ok but the lambda reads low when cold.
Apparently the ECU's run open loop when cold so in theory the lambda sensor is ignored.

Anyone got any ideas please?