yz 125 running weird

I have a 2003 yz 125 and i just started to noticed that when i take off and go threw all the gears floored, that when i pulling in the clutch and come to a complete stop my bike is idling really high like im holding the throttle a quarter of the way open. But when i take back off in first and go a foot and stop again my bike goes back to idling fine. I also put a new piston and rings in my bike recently and it did not change anything. I adjusted the air screw alot but it didn't change the high revving at an idle after riding my bike floored. What could the problem be?

How can I do a vacuum test on my bike? Or do i need to take it to a shop that already has the tools to do it.