Sounds like a throttel issue. maybe you have something slipping? Do you use a bell crank set-up. I have a G-62 on my Stinger that you see on the left. I had high idle issues, But was able to get it to a nice low idle using a 440 rod for throttle and using a home made bell crank system. Look and see if there are any binds gfoing on. Check the throttle crank on the engine..Did you take the spring off?

Try to redo the throttl;e linkage all together. I know I did...Where I have my 625 servo was an issue up aginst the Fuse and I had to really secure it in there!...DO NOT USE GOLD ROD!

Use 440 rod and ball joints if all possible.. If not 440 clips...Sloder the ends on. You will have a throttl;e system that will last longer than the plane I
I'll bet!