My bet is intermittent signal issues with either your camshaft position sensors or speed sensor( crankshaft sensor). Other possibility is fuel pump priming issues which could be caused by dirty filter or problem pump. Generally you should get a CEL if the sensors are on the blink. Any of the three sensors if faulty can lead to long cranking time. If the speed sensor goes bad car will never start or shut off if driving. If one or both camshaft sensors goes bad car will take a very long time to crank. The sensors are nothing but magnets with an electronic component that sends a signal to your ECM on camshaft or crankshaft position. Helps the car crank quickly when the ECM knows which piston(s) are TDC fires those first.
