Chainsaw Repair

When you hold the throttle wide open the saw goes down to idle release the trigger and you can rev it back up again but when you hold it wide open it idles down again. I looked and the linkage is operating but it cuts out when full throttle  Local saw shop done full service and said it was fixed but it isnt.
Any ideas on how to fix
https://www.youtube.com/watch?v=RBzTZekqn8g&feature=youtu.be

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 Havent watched video yet so cant say anything. Kevin




I got it fixed I had the top off and linkage works fine when not running, then i started it and reved it up,  when it cut out i seen the linkage rod move. I took it apart further and they had it put together wrong and when you rev up the saw the vibrations made the rod move out of place. 

Sounds like that shop hopes you prefer to buy a new saw...