If oil is only getting in a few cylinders wouldnt those be the only ones with fouling problems?How can every plug look the same?And if the intake was leaking at the bottom by the lifter valley,wouldnt that cause oil to seep into only the runners that were not sealed?I have taken the carb off and looked with a flash light down the plenum to were the intake meets the heads and they all look clean.Could all 4 carbs(which 3 of them were used not new)have too rich of an idle for this motor?