Repairs Help repairing commercial 22260

I have a 2003 or 2004 commercial lawnboy 22260 which starts up and runs for a while then acts like it runs out of power. If I let it set for two or three minutes it will start up again although reduced RPM. Again it will gradually slow down and run out of power ...can anyone help me Isolate the problem… don't know if it's a carburetor, issue possibly a float… Losing compression… Or plugged muffler ... Possibly reeds...
Are there any easy ways to help me narrow the issue down? Possibly some common problems?
Thanks!

Repairs Help repairing commercial 22260