[V6-12v] Rough Idle

[David Torrey]

Well, I replaced all spark plug wires and the rough idle persists (wires had 180K miles on them).  Plugs are new. I checked vacuum connections and can't find any issues.  I have noticed that after the car sits for 8 hours there is no vacuum assist for the brakes until the engine runs for about 30 seconds.  Not sure if this maybe related?  Possibly check valve faulty in the vacuum line going to the brake booster? Could it be fuel injector seals leaking air or MAF sensor?  Any experiences appreciated.

David