A couple of different things come to mind. It sounds as if your engine is flooding while it sits. The injectors could be leaking down when sitting putting more fuel into the engine that it can burn on startup. Another possibility is the fuel distributor plunger is leaking fuel into the intake manifold as it sits. When dealing with a hard start issue it is a good idea to check rest pressure as a failing accumulator could cause starting issues as well as a failed fuel pump check valve. I'd start by checking the fuel pressure as it sits, it should hold around 40 psi. If that pans out then check the fuel dist for fuel leaking into the manifold and have the injectors bench tested to see if they hold their rest pressure.