Engine won't start! (HRR2163VXA self-propelled walk behind)

[Crunchy409]

Final update!

I bought new gaskets (perhaps the missing secret sauce) and used Carb Cleaner + air pressure (for the first time) and these two factors together resulted in a mower running better now than it has for 5 years!! Thanks all for your encouragement and direction

 

[Crunchy409]

Unfortunately I have to partially take that back...

The mower will now typically start up great, but at least once every 5 minutes it will try to die. I have to put it back into choke, until it starts to drown on choke and then it will stay just fine again on idle. When it's idling well, it's idling better than it has in years- no sputtering at all... but it will frequently just die out, almost as if I had turned the throttle all the way down.

Is there an adjustment that I need to make on the carb? Any other avenues of troubleshooting that I should attempt?
thanks!!