Ok, heres the problem. This just started a few days ago. I changed the oil for the first time that season and ever since then i had a problem. The problem is that the mower will not idle right when the blades aren't engaged. But, when the mowers blades are spinning it runs smoothly. I recently bought alot of new parts to replace on this mower such as, spark plugs, blade, air filter, pull string etc, I didn't put any of these on yet, because they didn't come in the mail. Do any of you think its because of the spark plug? When i took it out it was black, but worked. (i know that it's time to change it) So would it have anything to do with the sparkplug? or airfilter? Any help would be great..