Mercury Outboard 3-cylinder it turns off if I put in neutral!

Hello,
I have a 1988 Mercury Outboard 3-cylinder, 80 hp engine ELPTO Sn.9527112 on my boat. After 3 years
with the boat stops, I throw in water and unexpectedly the engine has started almost instantly.
After playing for about ten minutes, I put in neutral and immediately went off the engine and
it is no longer restarted.
The next day I tried to restart it out of curiosity and is immediately started.
I tried many times to turn it off and restart it always stationary and is always restarted.
I came out 5 min at moderate speed, but when I put in neutral, the engine stalled and no
reboots.
This happened 3 times, then I took it off the boat and I checked if there was a spark on the
spark plugs, but what I thought was absent.
I had previously already changed a control unit and a stator, but unfortunately they sold me
a black stator..... I later learned that he had been replaced with the red by Mercury, because the black one was faulty.
I noticed that by measuring the battery charge voltage with a digital meter, the tension mounts >17Volt at 4000 rpm, it is normal ???
Thank you

Sounds like carb idle adjustments are way off.

Jeff

sorry, bat no: took it off the boat and I checked if there was a spark on the
spark plugs, but what I thought was absent.