Pull one of the coils out and stick a spark plug in it, then ground the plug to the engine case, should be able to see a spark if there's one there. If your engine is dirty or painted (like mine) you'll have to take a jumper cable and ground it to the negative battery terminal or the car body.
If you have spark I'd look to the fuel filter and/or fuel pump.
If you don't have spark I would check the security light just for the hell of it. While cranking the engine the security light should be out, if it lights up solid then you have a NATs problem.
Anecdote: when I swapped my engine it worked fine for awhile and then I lost the ability to start seemingly out of nowhere. I had no spark from the coils. I checked and changed the sensors like you, no luck. I ended up redoing all my grounds including adding an extra ground to the transmission case between the crank sensor and the starter right to the negative battery terminal. I also changed the ground to the tranny case and it fired right up and has been happy to start ever since.
2001 Nissan Maxima GLE