3 hp Briggs and Stratton Poor starting hot or cold. needs lots of choke.

3hp Briggs and Stratton engine hard starting when cold or hot but runs well when going. When cold you have to take air cleaner off and place hand over top to get to start. Even if hot hard starting. Did fit new diaphragm to carb and cleaned out. But runs nicely even idles nicely when warm. Any ideas appreciated