Kohler 149 cc Engine problems on Husqvarna walk-behind mower.

Seems that lately I start the mower and it appears to be running very low RPM. I recall that it was higher last year when mowing. The oil and air filter and blade have been replaced and it almost seems to be running rich when it is first started. when getting into thick grass engine strians more than it used to when mowing last year. Any suggestions??

Try a new air filter.

This sounds like either a dirty carburetor, or a problem with the governor/choke. Spray some carburetor cleaner directly into the carburetor. Check to make sure the governor and linkage is moving freely. and that the choke is working properly. If the engine has an internal governor control, it may need to be adjusted. There are links on line that will show you how to adjust it properly.