Hay,
my car does exsactly the same thing mate, its also a H reg 8v.. hummmm do u thinik thats a coincidonce??
i got my mate to have a lookie at my engine coz it just sits there idling for a few mins then calms its self down, it also does this when im in traffic..humm i still havent got to the bottom of this yet...
bloody annoying though if u ask me!