Polo MK4 idle help
You didn't spray some more carb cleaner down the TB once you fitted the new temp sensor did you? Dunno why it would idle at 900 and then creep up after a while of driving?! Unless there was so much carb cleaner already in there that it buggered it up again. Don't take my word for this but has the lamda got the same effect on idle as the temp sensor? If so then that could be knackered?