Now i have fixed my idle issue, i have found a new one. When riding, and changing gears, it seems to hold revs for a few seconds, and then drops down, i usually just make slower gear changes, so it doesn't 'bang' into gear when the clutch comes off.

Any idea on what it could be, and best way to fix it?

Are you physically pushing the throttle closed for like half a second right at a gear change?

Pull clutch, roll throttle closed, click up a gear, let out clutch, roll throttle open. its all very fast but once you get it, it should give you smoother gear changes.

It raising in a few RPM is just probably the rolling resistance isn't there any more when you pull the clutch in. you're also probably twisting the throttle open a little too. but I don't know unless I can ride/hear the bike itself its hard to tell. try what I said above, and if it's still hanging then its something else.

If it's only when changing gears then I'm inclined to agree with J_walker on that it's probably your technique.

But if you rev it in neutral and it experiences a "hanging idle" it's most definitely something mechanical, likely vacuum related.

If you want to help with this, what you need to do it back the throttle off just a 'smidgin' BEFORE you pull in the clutch, not after. The revs will drop, which is what you want.
If you pull the clutch before, or as, you back off the throttle, the revs will tend to rise or stay high, which is the problem you have now.
However, you do need to let an experienced soul try it to see if it is your technique or whether it's a mechanical problem.