The misfire at idle once the car is running properly is very, very slight and doesn’t always happen.
I did have a flat battery a couple of months ago having not used the car for a while – the breakdown guy at the time said my battery was fine and didn’t need replacing.
The car went into limp home mode once a few months back and I remember noticing the first signs of the engine idle problem then. The lack of power at the time it went into limp home is very similar to the lack of power I’m currently getting on first start-up i.e. I have to put my foot right down in first gear to move off from lights in the first few minutes of driving. I’m guessing this lack of power is because the car isn’t running on all cylinders.
For info, my garage couldn’t replicate the fault when it first surfaced and to be honest don’t seem to be specialist enough for me to spend money on an attempted diagnosis. I have also posted this on a VW forum so might get some additional suggestions there. I’ll post any outcome here in due course in case it helps someone else.
Thanks again for the suggestions. It’s an old car but I’m kind of desperate to keep it on the road!