Engine Idles Too Low of RPM,Stalls

Hi All, I have a older John Deere push mower,self propelled. Engine model JS45
875 190cc Briggs engine, The mower was running well. I did hit a rock and the
engine stopped running. Put mower on its side and blade looked out,turned easy.
The engine will start but it now idles at a real low rpm and then stalls.
Where do I start looking. I do not much small engine experience at all.
All help is greatly appreciated.
Thanks
Jimmy

Start with the correct model number for the engine. It is etched or stamped into a plate on the engine.
https://www.jackssmallengines.com/jacks-parts-lookup/briggs-stratton-model-locator.aspx