hard start 560 sel
when it reduses to start, does it pump out black smoke when it does go? It sounds like it is badly flooded. A leaking 'cold start' valve can dribble a lot of fuel into the intake when it sits, and voila!! you have a flooded engine.
If the fuel distributor was leaking, it would do it all the time, not just evey now and then. I suspect the cold start injector. Check it by removing it from the manifold. and then activating the fuel pump to see if it dribbles at all.