Revs Rising and Falling on Startup

[roboblob]

May help someone.. you never know

Over the weekend I decided to tackle the vacuum hoses to try and stop the annoying revs issue on startup from cold.
So I replaced all of the braided hoses and other ones which were a bit too loose for my liking.
With anticipation I gave it a turn over..... Still the same

So to check for leaks I disconnected from the manifold and added a length of tubing and sucked and stuck my tongue on the end to block it.. the vacuum did not drop.

I then noticed the small black and white non return valve just after the manifold, so i took it off and guess what it allowed air to pass in both directions with no restriction at all..

One non return valve later my rev issue on startup has been cured.