I think I should clarify my earlier post. I don't have much Sube specific experience, but I have been around several carbed vehicles over the years that would diesel and if the idle was slowed down it stopped. I don't know why, possibly the increased speed draws in enough extra fuel that glowing carbon deposits light, or (?) whatever, but it should be simple enough to slow it down a bit and see what happens. Easily reversible if it doesn't change anything.