Limp mode?
It is either limp mode or your rev limiter is stuck. I'm not really super familar with your model ski, but if it's your limp mode, you should have some knowledge that something happened. Like if your ski is equipped with the message center (LCD) panel or by how many beeps you heard. I know if your overheating, you'll hear a continous beep.
If you have forward, neutral and reverse, then your neutral switch can be sticking. This switch limits rpm to 3000 while in neutral so that you don't start while in gear and run into something.
I can't seem to get to my manual that would allow me to give you a better idea of what's going on. I hope to have my problem resolved soon so I can better assist in trouble shooting. But I think the above generic ideas may point you in the right direction. This is probably a simple problem, so don't make any big drastic changes without checking the simple stuff first.