At the beginning you say lots of fire but then no fire and you replaced rotor and cap no fire?
Check the wiring to the dist. and inside for anything loose that could make contact and then loose it. No I do not think its your key system.
Also fix the knock sensor, it has to do with the fuel system.
Hope this is helpful Mike
Shift lock is just a safety feature, so you have your foot on the brake, when you put it in gear. It has nothing to do with starting the car. Intermittent starting problems can be a few different things. Ignition switch, park/neutral safety switch, wiring, and corrosion. If it clicks when trying to start, it cold be loose/corroded battery cables or a bad battery.
Sorry to the bearer of bad news but i have a funny feeling your ECU unit has failed ,where is it located on this vehicle anywhere near the engine where it can get hot?
camshaft sensor, crank shaft sensor. possibiltys. do you have a computor chip on your key, if so do you have a secound key? it is possible the key chip failed, if equipet
Here's a link James on how to replace,join the site,it's free,then you can use there repair guides like me.I have a silver 85 Nissan 720 4x4,here's a video to see.