Check the battery terminals are tight, I had this problem once on mine and found one loose.  Problem went away after it was tightened.

Thank you

I know on the 800 you could turn the blower nut to get the valves where you wanted to check them. What do you use on the 950 to get the valves where you want them???

We didn't have much free time last year so only went that high once and I did do it then but didn't seem as bad. I have not stopped and shut it off for a bit. Honest was to nervous haha

Also it's a 2020 Z950 with 2400 miles. No modes other than wheels and tires.

Went on the mountain yesterday got about 7000ft elevation and started surging while cruising. Turned around and let it idle but continued to surge up and down. Got halfway down and she run like a dream again. Went back up today and did the exact thing. Checked spark plugs while up there and Things looked good. Come down run like a champ again and checked valves and they were perfect. Any help would be greatly appreciated