Evinrude 15 hp 4 stroke idle issue

[Coach955]

model year 2000 15 hp 4 stroke Evinrude outboard. Has a vacuum or air leak and will not idle below about 1500 rpm unless you pull out the choke. Carb has been cleaned and everything set to factory specs. Replace all carb to manifold gaskets. Only other possible place for a leak is at the manifold to cylinder head gasket?

this one has me stumped.
help please

thanks

 

[racerone]

Check the rocker arms on the cylinder head.-------Check valve clearance.

 

[Coach955]

fail to see how that will affect idle. This happened overnight. No noise from valve stems when running indicating too much clearance.
Please explain..

 

[racerone]

Never mind then.--------Ignore post # 2