I bought an automatic 02' IS300 about a week ago with 183k miles on it. Driving it home was fine, noticed an oil leak from the valve cover gaskets. Then about 2 days after I got the car, it's throwing misfire codes at me. Never owning a Lexus before it startled me. I'm not sure if it's had a misfire code since I reset the codes because I don't have an OBDII. But I was wondering if it's just an intermittent misfire since it had too much load. Been driving it slow and steady ever since I found out about the misfires. Help pls.