Won't start when hot - classic Audi!

[randall977]

This is a classic Audi problem. My 200 5E starts fine apart from for half an hour after its warmed up. It refuses to start and then suddenly when the temp drops to a certain level is fine again. My two suspects are the warm up regulator and the auxillary air valve - both have bi-metallic strips. I also have a slight problem where the revs go up instead of down when the engine warms up - I suspect the two things are related. What should I replace first - the fuel enrichment device or the air enrichment device? or could it be something else... (btw it's not the CSV).