Kohler Courage 27 SV740S- Oil from Breather

I have 2007 Cub Cadet GT1554 with about 275hrs on Kohler Courage 27,I am third owner and service it every season and has run excellent till now, recent oil, filters, plugs changed beginning of this season, was running ruff felt like it was struggling and or not enough fuel, cleaned carb, checked fuel pump, new gas with additive for ethanol. Checked reed in breather cleaned it flipped it and sealed it. Now questioning if all issues lead back to the fact I have excessive oil spitting out of breather ending up in airbox, more than likely i'm assuming cause issues listed above. Was hoping someone could give me list of possibilities of what could causing this, Thank you in advance,





Graham