New engine was running fine for 7 flights.
After that it was stored along with the plane for about 4 months with no activity.
Now upon resuming the activity, engine is very hard to start and does not hold idle.
After idle stables, after 30-40 sec engine stops.

Plug = OSF new
Feul = High performace Heli 30% nitro
Prop = APC 17x12 Wide
Header and Tune are Hatori 821 and 822

Please advise.
Amram Leshed