Engine runs rough when warm

[johnsms3]

Greetings,
I'm having an ongoing issue with my MTD lawn tractor with a Briggs and Stratton engine.

Briggs model number is a 31A607 I/C.

After about 20 minutes of mowing it starts to run rough, spits, surges, then eventually dies.After waiting an hour I can go out and essentially repeat the process and eventually get my lawn mowed.
Obviously, this is very frustrating to say the least. I've taken the carberatuer apart and cleaned it multiple times and have checked that it is getting spark.

I'm essentially at a loss at this point what could possible be causing this.

Any advice would be appreciated at this point.
Thanks in advance.

 

[bertsmobile1]

The instant it stops , check for a spark.
If you have one todd a SMALL amoutnt of fuel down the carb.
It it fires right up & just burns off the fuel you tossed in then suspect a clogged fuel tank outlet or bad fuel lines.