Small Engines (Lawn Mowers, etc.): Onan P218g engine, head gasket, leak down test

Question
Hi,
I have a 1988 518H Wheelhorse garden tractor with a Onan P218g engine on it( Nikki carburetor ). The engine will start and run just fine as long as the choke is 3/4 closed. The engine will not idle if the choke is completely open, but will run at full throttle with choke open. I cleaned and rebuilt the carburetor, but engine continues to run the same. Engine does not appear to be smoking at all, so I assume that rings are in good shape.
Any info. that you could give me, would be much appreciated.
Thanks,
Dave

Answer
Are the intake gaskets leaking?  Have you performed an engine leak down test to see if a head gasket may be leaking?

My guess is the carb is still the problem but I have had a leaky headbolt cause this problem once.  Took me forever to find the problem since most idle issues are the carb or gasket.  I have had to clean a few carbs several times to get them to work.

Did you blow compressed air from an air compressor through all the carb orfices?
Eric