Won't start causes
Here's all the causes behind the "earlier would stall, now won't start" problems.
Clogged fuel injectors
Clogged fuel filter
Clogged catalytic converter
Bad sparkplugs
Stuck valve on EGR valve
After a few weeks of thinking and diagnostics and testing, we've come to figure it might be the catalytic converter.
Replaced fuel filter, pressure tested as good.
Cleaned the EGR valve. EGR valve seemed functional before cleaning.
Engine mistiming does not agree with 1) stalling leading upto the engine no start and 2) cat code thrown on the car scanner device. This was offered as another explanation for "engine misfire".
Scanner also suggested problems for HVAC, EVAP, and EGR among a few others. I was told by an expert, that catalytic converter clog can throw a bunch of different codes like that.