Every now and then when I am driving, and rpm's are at 3,000 for a few minutes I get an engine light throwing codes for low fuel, random misfire, ect. I read online it could be the crankshaft sensor, but I know the o-ring is bad cause oil is leaking down the front, and bottom of the engine. Could the o-ring also cause that?

I replaced the spark plugs, wires, coil pack, ect. Its a 2003 base cooper.