GT48xls fuel/exhaust problem

[Bjw903]

Hello. A few weeks back I was mowing some fairly tall grass. I was going slow and taking it easy. After a while the pitch of my engine changed suddenly and it seemed like the power changed slightly also and I could smell fuel pretty strong and exhaust. I never have before. 10 minutes later it changed back to normal. This went back and forth for another hour. Now my mower sounds that way every time I mow and I smell fuel. It sounds like when you take the baffles out of a motorcycle. I’ve changed the air filter, fuel filter and spark plugs to no avail. Any help would be appreciated.

 

[ILENGINE]

If a twin cylinder engine need to check spark when the engine is acting up. Could be loosing spark intermittent on one cylinder.