Is this sentence in Chinese the original one? Because it sounds weird and has some obvious grammar mistakes. But what you wrote indicates that the english version is the translation, so I'm a little confused. If the english version is the original one, I'd consider my translation to be: 我宁愿为挽救某人而献身也不愿意让他死去。 as for the modal particle 嘛, in fact here's a detailed article just on italki: http://www.italki.com/article/277/perfect-your-street-chinese-4-meanings-of-#.V and the explaination of the usage of 啊: http://resources.allsetlearning.com/chinese/grammar/%E5%95%8A and some other modal particles: https://www.chineseboost.com/grammar/ma-ne/ hope you'll find this helpful.

I would rather die while saving someone than let that person die. -------> 我宁愿为了挽救别人的生命而死。（By the way 顺便说一下/顺便说一句, if so you'll not be so American: the American would sooner let others die for themselves than die for otheres, and what is worse, the American would kill more than a dozen of innocent civillians without hesitation in order to kill a terrorist. The American are given to give lessons about Human Right to other nations while all that they do only is just tell the world that, yes, there is something called human rights, but they belong only to the american. As to othere peoples, they do not have human rights and they even do not need this kind of thing.

我更情愿用我的生命去挽救那些人，而不是他去。

不对