My two cents you may be running rich. Due too bad float height this doesn't show up when the engine is cold because then she likes to be a little rich then and when its warm it'll show up as high idle but then as you use up that little bit of extra overflow fuel wh atever you may get it back down to where you want. Still probably running a little rich would also explain the dieseling, which I always associate with poor fuel mix (overfuwl) causing glowing carbon deposits in the combustion chamber....or so I've been told.