If the derailleur is bent then a replacement can help.

But if it is not bent then the issue is entirely with your setup and a new derailleur will be a waste of money and you will have the same problems if a new one is not perfectly set up. Front derailleurs are much harder to adjust than rear ones - even higher quality. FWIW, RSX is very good quality.

If you think it is bent can you bend it back to how you think it should be?