I am thinking that maybe it was the fuel door lock mechanism that is vacuum driven. You might have had a leak going on there, affecting performance.
If this is not the case, I will need to see if I have one of those magic buttons on my cars...

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D