1994 skidoo 470 takes off

so i bought the sled and when i first got it to fire up it revved higher and higher then took off on me. lucky i could hit the kill swt before it was gone. so i cleaned the carbs and threw it all back together. i drove it a couple times, no problems. then just today i went out and revved it up crusiing down the road then it just revved higher and higher and took off again. again i hit the kill swt and brought it home. any ideas?
im thinking maybe the cables? thanks

1994 skidoo 470 takes off