McCulloch Chainsaw won't restart when warm?

McCulloch 2318, starts right up when it is cold.

It will continue to run as long as the throttle is maintained.
When it stalls, it won't restart for a while.

I replaced the spark plug and cleaned the air filter and carb.

I follow the restart directions, i.e., pump the primer 10 times, set the choke at 1/2. It doesn't seem to matter if I pump the primer or not; if it has started recently, it won't restart.