I have a related issue. I just replace the driver's side valve cover gasket on my 94 4runner because it was leaking oil. After replacing the gasket, when I started the car, when parked shot up to ~2300 rpm. It seems like there was more compression since the oil guage show an increase of pressure. I adjusted the throttle and was able to lower it to ~1500 rmp. When I started driving, the engine seemed very rough and after I parked the car, I still saw oil dripping but now from the valve cover that was just replace. I had not had the time to look yet but any suggestions on why the engine is running so rough? Thanks in advance for the feedback.