Older Tecumsen

It's on an old wheel Horse tiller; had it for many years, in the past had to rebuild the carb. run great after, but this year getting it ready for the garden work it will start but won't stay running. How I've cleaned the engine before I started working on it with the hose, then took carb. cleaner to the carb. Let it dry a day 24 hrs. in the hot sun, fresh gas, cleaned the plug, changed oil, fresh air cleaner, made sure everything was tight, fuel lines no leaks or cracks, completely new fuel, cleaned the sediment bowl! It will start but dies after a few seconds running. I am out of ideas.
 
THANKS, Mtman725