racing

I'm hoping for some second opinions on a saw diagnosis that I've done. I got a Stihl 031AV that has recently had the carb rebuilt and was running successfully but now the saw races at idle even with the idle screw backed all the way out. I am suspecting an air leak but I have no tools to test...

So whenever I start my Remington Outlaw (46 cc, 20" bar) chainsaw for the first time that day the chain spins super fast, like full speed and continues to run at full speed until I press the throttle. I tried to use the chain brake for this simply because I didn't like it spinning so fast...