According to the manual your not supposed to touch the exellerator pedal when the engine is cold and your supposed to press it half way down when starting a warm engine.
however, everytime i give the old girl some boot, this seems to change on my car, i can start my car fine in the morning and the choke will control things perfectly, but if i give it some hammer, when i come to start again it struggles to stay running (as if its got no choke) check your engine coolant temp sensor as this controls most of these sort of things