I would think that a contributing factor to your truck running better when it is hot than at start up, is because everything is fairly sloppy when it is cold and therefore compression is a little reduced. From what I understand, the slop is necessary, because of the extreme temps in the combustion chamber (heat make the metal expand).

ok ok, I know "slop" isn't a technical term, and it's not really slop, it's more generous tolerances.

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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