The next step would be cleaning the throttle body, that could cause this problem and if that doesnt help monitor fuel pressure when this happens and check for vacum leaks. Let me know if you have questions, thanks.
If its leaking it should be leaking at all times so around the intake gaskets, throttle body gasket, and vacuum lines. You can use carb cleaner to spray around to see if it changes idle speed if so look in that area. If fuel pressure is low replace the pump and pinch off the regulator to seee if that helps if so replace regulator. Let me know if you have more questions, thanks.