Problems with 07 Suzuki Gs500 High Idle at stops?

I have a 2007 Suzuki Gs500 and recently I found it idling high after about an hour or so riding. I doesn't do it all the time, just sometimes. - Shoots up and stays around 3000Rpm.

I read online about trying to adjust the idle screw when the engine is hot which is suppose to be set around 12-1500RPM. But I am not sure if that will work because it possibly stall out during cold starts.

Another idea was a carb balancing - I just bought the bike in March with 6500km and I put 1000km on it, should it need to be balanced? I would think the dealership would have done that.

One last idea was an exhaust valve adjustment? Not sure what that entales but it sounds extensive.
The dealership I got it from said they can look at it for $95/hr.

Although I am new to motorcycles, I still have some mechanical abillity and looking to save a few bucks. Any sugestions would be great.

One last thing. What is the top speed suppose to be? I heard some say 180km/h - But I had mine up to 140 today and it didnt seem to want to go anymore. It sat around 6000Rpm