I have a MY00RS with an intake and exhaust. It's got 12,000 miles and I'm not gonna lie, I run the crap out of it. My problem is when I took the air filter off to clean and oil it there was motor oil in my intake. Is this caused by crankcase pressure because of long runs at high RPM? Also, my car is running extremely rich(I know, I know....all 2000's do). How can I lean it out a little without getting a S-AFC?

Basically, yes. Lateral forces also contribute because of the horizontal layout. There are a pair of breather hoses that connect to the intake box.

It shouldn't be running that rich. I have an intake and exhaust on my MY00, and my EGTs are almost optimal. It's not worth spending money on the AFC, IMO.