Small Engines (Lawn Mowers, etc.): craftsman 6.0 easy start losing power, ozone pollution, air filter

Question
It ran like a champ yesterday. Today about 20-25 mins. into the backyard it starts losing power; sounds like running about 50% -- still cuts grass but feels like it's missing and trying to quit. Gas was full and not running hot, but it was a hot day and a code red ozone/pollution warning. Could that affect the timing/power? Had it in for service last winter.

Answer
Let me guess.  You cleaned under the deck recently didn't you.  You tipped the mower the wrong way and filled the air filter with oil.  Remove the air filter and see how she sounds.  Always tip the mower with the air filter UP.

Ozone and heat don't mean squat. Not the problem.

If the oil filter isn't the problem reply back and we will dig deeper.  We have to start there. I have 10 customers a week with this exact sme problem. 10 a week!