Car will crank but will not start

I was driving down the road everything was fine, suddenly it got kind of sluggish and then just quit running. I pulled over to a safe place and gave it a quick once over then tried to start it, but it would just turn, never cranking. After getting a friend to pull me home I proceeded to check for spark (good), check fuel pressure just past the fuel filter (good). Also, not sure if related but prior to the car was taking a few seconds longer to start.

Since then I have replaced the following:
-Fuel pump and screen.
-Spark plugs and wires.
-Rotor and cap.
-Crankshaft position sensor.

The starter (least likely candidate I believe since it is not clicking) was changed out three years ago, and the alternator was changed out eight months ago (possible, but not sure as I have no way to check it).