"If you would just listen for a moment…"
"If you would listen just for a moment…"
Subtly different meanings, but in both cases 'just' is adverbial. In the first sentence, 'just' modifies listen. In the second, I think the whole phrase 'just for a moment' is adverbial, but no matter. 'Just' is moving around as you would expect from an adverb.
But what about "If you would listen for just a moment…"
'Just' is no longer modifying 'listen'. It isn't behaving like an adjective, it doesn't really modify 'a moment'. Yes, we can call it an adverb, given that 'adverb' is a bit of a catch-all category. But what is it really, what is it doing, what is it modifying? It doesn't really modify anything specific, it modifies the whole situation. It's more like a kind of intensifier or attitudinal word.
Does someone have a clear grammatical or linguistic analysis of this situation?