I agree the carb is the first place to start...but I'm not ready to rule out other culprits. With respect to the carb....if it idles well (as my tractor does) I'm guessing I really just need to concentrate on the main jet as this is what seems to be not working correctly (although I can watch carb cleaner spray out the main without issue).
I'm letting the carb soak for 2 hours, hitting it with carb cleaner then compressed air...then repeating this process. I plan on doing this for much of the next 24 hours. If I'm gonna clean this bad boy I need to know I did a thorough clean so I can potentially rule the carb out soon.
Any other tips of the trade you can share to help bring this mower back to life?