Trouble starting

If it cranks over sufficiently fast enough but doesn't make an attempt to "fire" it has the two most likely problems could be either a weak ignition system or losing its prime for fuel. Its hard to identify which without doing some basic diagnostic test. Worn spark plugs or ignition insulation breaking down, would be the common ignition problems. A coolant temperature sensor reporting the engine coolant temperature is warmer than it actually is could be a problem with slow or difficult starting. A lot of sensor readings can be read right off a scantool without having to do intrusive testing at each individule sensor on the engine.