Thanks for the insight!
Another thought (forgive me if this is way off track): Could the issue be made worse by vacuum leaks elsewhere on the car - away from the engine? Reason I ask: I had the door panels off a month or so ago and noticed that on two of the doors a bunch of the central locking parts/hoses were missing. No idea why they're gone (and I didn't even know the car originally had central locking until then!)
Or is this a whole separate vacuum circuit? Apologies, I'm a novice when it comes to vacuum stuff!
Thanks
