what kind of plugs do you have and are they new (if you have crappy plugs [bosch plugs on our cars don't work well] and you are not getting a good enough spark along with you running extremely rich can cause stalling and non starting)

my method of solving the myriad of engine starting problems is to slowly eliminate each possible problem kinda like you did so i'm just following along other obvious problems...this is what it is leading me to believe but just based on knowledge above i of course could be wrong...but this might eliminate other concerns