So here's my problem, my bike will not idle between 1000 and 1500 rpm with out the bike hanging in rpm when I rev it. Then when I get it so it doesn't hang, it won't idle. So here's what I was thinking about checking, and would like your input on it. 1) if there are any vacuum leaks that I may have missed, 2) are the fuel/air mixture screws set properly, 3) check the valve timing, 4) fix the starter/kill switch housing on the handlebar (it can rotate on the bar) and then adjust throttle cables.

Is there anything else you can think of that I should check? It's a 2009 GS500 with about 27k miles on it. The only maintenance done was a new chain (cleaned and lubed properly) and oil changes according to spec.