2005 G35 Coupe automatic - stock aside from a full HKS clone exhaust and cold air intake, & a sound system.

I've been having this issue for a while now but it seems like its getting a little worse. When I pull up to a stop light usually after driving a bit, and idle, the car will sometimes misfire or hesitate / buck a few times. Only at a complete stop, at idle. It does it on and off, and runs good otherwise with no misfiring or check engine lights etc.

Ive had the mods on the car for over a year, it just started doing this recently so I know its not from the intake or anything. I recently changed the spark plugs and radiator, ran good after that too.

It feels like a semi hard misfire when it happens. Like the rhythm of the engine/exhaust sound gets interupted for a second a few times, then it stops.

What could this be? When I changed the plugs out, I noticed one of the wells was filled with oil - I think I need a new valve cover or gasket to fix that.

I was thinking oil may be getting into the plug and causing that momentary interruption of spark, then it burns off, but not sure..

Any help is greatly appreciated 🙏

 

Pull the coils and see how much oil is back in the well, yes oil saturation will cause a misfire, you can temporarily fix the issue by pulling that plug so the oil drains into the cylinder and wiping down the spark plug and coil boot.

 

Clean your MAF sensor.