if it's fucked then it's fucked. No amount of flushing will fix it. As its especially getting so hot so quickly I personally wouldn't bother with it. I've had the same thing on a few cars and ended up getting them recored which in hindsight I should have done straight away.
Otherwise Shouldn't be too hard to find something similar, but I think I recall seedy saying he thought it was pretty small so a good chance to chuck something bigger in!