I am going to make some conclusions,I interpet “intake valve leaks” to mean the valve stem seals are leaking (sympton would be smoke at start-up) not so serious,but would not cause rough idle,I hope the situation is not your intake valves not seating (sympton would be low compression,loss of power,rough idle) this is serious.
The “tube from oil pan leaking” could be the cause of your rough idle (engine vacuum present in crankcase,by design) I can’t tell you how hard this would be to fix as it is most likely some type of seal (cheap part,labor intensive)