99 sentra 1.6 no start known causes?

[glitched]

first let me say i don't mind throwing cheap parts at this car. it has 165,000 miles and girlfriend has a 60 mile round trip commute and works 2nd shift. so if it doesnt fix the problem, then its just one less thing to go wrong on a long commute in the middle of the night.

So with that said, i believe i have air gas and spark, but no start. (it died while driving down the road)

gas- i just tried replacing the fuel pump and in-take lines. all 4 plugs are wet with gas after cranking, but still no start
spark- new plugs, cap and rotor. timing light flashes on all wires. waiting on a couple used distributors on ebay to see if maybe it's weak, or if it's the built in sensor.
tiny bits of stumbles, but no start, dial on the rev counter wiggles, i've read it wont if it's a bad sensor.
I even tried pulling the o2 sensor just in case the rare event of a clogged exaust/cat may be causing a no start. when i do that i hear only maybe 1 "bang" / fire per crank
main o2 sensor has been replaced in the last couple years.

before it died it was throwing code 420, which is cat below efficiency, which i was chalking up to an exhaust leak between the o2 sensors.

My question is, what are some known common failures and fixes on these cars? (i've seen plenty of conjecture in my searches but few results)

[glitched]

Well s***. What a crappy design. Bolt holding rotor in place fell out and is stripped out