Toro mower 20333 very loud

[ZeeGee7]

Toro Push Lawn Mower 20333.
Serial number 311037736.
Year 2012.
Briggs and Stratton 128T02-3256B1.
VERY loud when idle. Seems like excessive rpms.

I checked/cleaned muffler, thermostat/choke, intake manifold, carburetor, not leaking oil, not smoking, starts great, cuts and drives nice.
PLEASE advise what else should Iook into.

 

[Bertrrr]

When did it start doin this ? Was anything changed ?

 

[ZeeGee7]

When did it start doin this ? Was anything changed ?

Nothing was changed at all.
I simply noticed higher rpms along with louder operating noise after 11 years of use.