Why does my explorer have trouble starting in the morning?

could be vacuum leak/leaks,or idle air control valve dirty.if no vacuum leaks,you could try cleaning the iac valve with some throttle body cleaner or carb. cleaner.don't get it in the electrical part.let it dry,and re-install it.see youtube video on how to clean it.

Is the engine light on? Could be what was already suggested - if the engine light is on we can pull codes and have a better idea of what system it is and possible fixes.