There should never be oil anywhere on the intake system. Sounds like you have a bad gasket/seat somewhere honestly. And yes oil entering the combustion chamber could cause a rough idle.
North East Honda Killer
OBX Header, Hi flo cat, dremled throttle body/intake manifold, k&n cold air intake, eibach 1.5" springs with Ford Racing gas strutsand Toms tune with PZEV delete and 91 octane