will that set up give me abig power gain in the low end and how much top end will i lose with that

 

It will give a little bit more torq you should not lose to much top speed. I mean you will lose alittle bit but if all you race is xc its not going to hurt you any.

 

I'd guess that you peeled the teeth off the front sproket, or the splines on the transmission output shaft are worn badly.
If it turns out to be a sprocket problem, you need to replace both sprockets and the chain, at the same time, or the new parts will wear out very quickly. I can appreciate not having much money, so perhaps you can talk to your parents and see if you can do some odd jobs and get them to help you out with the bill for parts.
Good luck,
Dave (38years old and parent of 2 teens)