yes.. what Scott said is the way to go but it is basically a new paint job also... More if your surface preparation is not good either. I dont agree with the try on a small piece first even if i RESPECT Pappy all the way!!...
The problem i see is that if you try on your valance, you are going to have a 99% chances it works good... I don´t think a new coat will "damage" your old sanded paint right away but the problem is that in the future, the more exposed to sun surfaces as the rood, hood etc will be the ones that tells you if your recoat came through ok or not...
In few words, if I were you i just start by trying to sand and polish as good as i can the actual paint job... As Don said, a good wet sanded till 2000 or 2500 and then polish can actually remove that particles sticked into your clear coat... It can be a lot better than it is now actually... Then, if you cant live with that paint job, go for Scott´s option and in that new trip, get a better body preparation in order to justify the new invest in time and money...
But if i were you i´ll start by a week of wetsanding and then, see what is the actual best result you can get with the paint job you actually have.
I didn´t read that you used one stage metallic paint... That´s the lowest line Mark... In the future try to always go for polyester base and clear coat and with the best brand you can get... at the beginning, it cost a LITTLE more but that is something you NEED to know you are using the best you can afford...