what is your engine idling at? maybe you need to adjust the residual fuel screw and idle screw.too little residual and i suppose the engine winding down could stall itself? are you leaving it in gear or coasting to the stop?
My engine has stalled out before with high power/boost.For me it ended up being the valve guide to valve stem clearance that was too tight.The higher Exhaust gas temperatures caused the exhaust valve's stem to expand and seize up in the guide.I'm not saying that this is your problem only that its is possible.