Hi All,
Thanks for your replies.
I have tried cleaning the TB in the past, it did run better, but still not right. It ticks over fine, never stalls etc all the time it is untouched, but if you then do something like turn the steering wheel sharply, or pump the brakes, it judders to the point of stalling - it doesn't always stall.
In the end, we took it to a VAG specialist that removed the TB completely and cleaned it up. He also cleaned up the throttle valve potentiometer contacts. This helped a bit, but he said in the end that he suspects it needs a new throttle valve potentiometer. TVPs are not available to buy seperately as they are matched at the factory, so a new one means a new TB. He didn't recommend getting one as at £330 plus fitting it was not an economical repair.
I found a cheaper new TB from a parts supplier and thought I might buy it. However, having now read up further, on auto models, the TVP needs to be 'matched' to the auto gearbox ECU - and this is a specialist VAG job (or maybe VAGCOM, I don't know). So, I'm not sure now.
The other things I was told to try were:
* Coolant temperature sensor - not sure where this lives, and
* Crank Speed Sensor.
We tried to find the latter at the weekend, but had no joy - if anyone knows where it is, please let me know.
Thanks again,
Stu