Honda rotary mower only runs oon full choke

This is an HRR216VXA self propelled mower that ran fine last time out. No changes in the interim other than cleaning the mower after last cutting. Used proper procedures rinsing and drying but???
Symptoms - mower starts beautifully but only runs on full choke. Taking mower off choke results in the engine sputtering and dying. Will run on full choke for 10 minutes(?) or so then dies. Won't run at that point whether choked or not.
Changed fuel to a fresh batch, checked and wiped plug, checked and cleaned slightly dirty airfilter. No improvement.
Sprayed cab cleaner in air intake and ran better briefly (probably burning the cleaner) but then back to only running on full choke.
Out of ideas at this point and would appreciate suggestions.
Other threads were big on replacing a plug that otherwise looks fine.
Thank you

 

Install a new Champion sprk plug. Hondas are finicky with spark plugs. They came with NGK, but NGK's don't seem to work well in them. Then Try running SEAFOAM in the gas.
If that does not work, then a carb cleaning will be necesary.

 

If you have a vented gas cap on your tank, make sure it is clear & clean. Blow some air through it so that it is not restricting the gas flow.

 

I agree with the last post. First thing to check is the gas cap vent. I have spent hours on small engines that start and run fine for a few minutes only to die. Usually find a plugged gas cap vent to be the problem. If not a carb cleaning is in order.

 

Thanks; will try this.
Had heard of the 'change plugs even though it looks fine' method but had not heard of SEAFOAM.