I have a 2004 Lancer Oz Rally and I've been working on restoring and learning on it. However I've run into an interesting issue. When the valve is connected with hose from the solenoid to the valve, it idles incredibly rough and can stall out or even no start. However when the hose is disconnected, It almost runs smooth just a bit higher than normal. Any ideas? Is it just clogged or is something else at play?

 

Could be being hung open by a faulty solenoid. Also improper vaccum line routing.