If this is a carby model look at the fuel pump
From cold, my engine starts easily using the choke and a bit of throttle. However, it will cut out straight away unless I keep activating the choke button momentarily, and once it's warm it's fine from then on. When it was last serviced, I mentioned that it had a tendency to backfire and stall at idle at times, which now rarely happens. So, could it be the idle mixture may be too lean now?
If this is a carby model look at the fuel pump
the fuel pump had a kit installed not that long ago, as it wouldn't pump enough fuel at high RPM. Even if the pump is crook again, there would be enough fuel in the bowls to keep it running for a while. It dies as soon as I let go of the choke. Still, may be worth checking again.
Check your idle jet in the carburetor
if its had fuel sitting around e10 or just gunk build up could be the idle jet or progression holes blocked up
possibly a airleak
might wind each of the mixture screws out a bit and richen it up, otherwise might be time to strip the carbs i think. runs perfect after a minute of pushing the key in and out!
Errics when u push the key in it activates the electronic choke its normal to have to bump it a few times if your not using the fast idle lever maybe check on youtube for the correct starting procedure for your engine the only engines i know of that are turn key and start are EFI engines
90 vro johnson 2001 model the very last would start and not need priming or choke to keep it running
never had to do it to any of 15 2 strokes ive had
somethings up with yours