bad idle when hot
Picked up a walk behind lawnmower from my mom, said she was having problems with it idling funny. Maintenance had never been done to it, so i replaced the spark plug, air filter and gave it some fresh oil and gas hoping that it would solve the problem, and of course it didn't. I have not replaced the blade, even though it is beat to **** and needs to be replaced.
So here is the deal. When i first start and run the mower, it runs great, good idle and everything. But after running it for a while the idle starts to go up and down.
Anyone know what could be causing this issue and how to fix it?