My 90 and 91.5 both start without touching the throttle, even in some pretty frigid weather. Both will idle chained & rolled tree stumps out the ground without touching the throttle as well.
I would check - in this order - air ingress into the fuel system from the tank to the injectors; leaking injector nozzles; a sticking dynamic advance piston; brittle/compromised rubber tips on your Fuel Shutoff Solenoids.
At the very least, screw a mechanical fuel pressure gauge into the bleed port hole in the fuel filter housing and go from there.
My '90 & a '93 I use for work will stall if you don't give 'em enough fuel starting.
