Yamaha 70BET0 idle issue

[Yammie70]

I know it's been a while but I just wanted to give an update and thank you all for your help.

I followed this suggestion and boom, the motor runs perfectly now !
A 5min fix that really made a whole difference...happy days

My 1999 c90 3 cylinder 2 stroke similar to yours started idling rough and cutting off a few years ago and I removed each idle mixture screw and sprayed carb cleaner in orrifice where screw was, then followed by some high pressure air hose in same hole, replaced screws setting about 1-1/2 turns out from lightly seated....and it fixed the problem!.... Must have been some trash or debris in those orrifices or circuits.....maybe give that a try....