If you are getting fuel into the oil, it could be a couple of things. First, if the fuel pressure regulator is failing, the pressure can get too high and leak from the injector when you shut the engine.
Also, a stuck or weak fuel injector can also cause this to happen. When an injector solenoid is energized, the plunger is retracted, lifting the needle valve off the seat. This allows the pressurized fuel to spray into the intake manifold. When the solenoid is de-energized, spring pressure closes the valve. Because of the year and mileage, I have a feeling the spring is too weak to close the valve and fuel pressure drains off when the engine is off.
I have a question. When you start the engine cold, do you ever see any dark smoke from the exhaust or an odor that indicates a rich fuel mixture? If my theory is correct, the engine is slightly flooded when this happens causing the rough idle.
Remove the air filter assembly and have a helper start the engine and then turn it off while you watch for a spray from the injector. See if it leaks off when the key is first turned on (engine off) and if it leaks when the key is turned off.
Note: If you have a lot of fuel in the oil, change the oil and filter to prevent bearing damage.
Let me know.
See pic below.
Monday, December 5th, 2022 AT 6:47 PM