To be honest, I think you are worrying needlessly.
The reason is that when a non-representational graphic such as yours is printed at a very large size (even up to roadside billboard size), even if a person is very interested in the design, the closest they will usually approach it is at a distance from which they can take in the entire graphic at one time. If they are *exceptionally* interested (say, another graphic artist), they may get a bit closer, but they will almost never put their nose right up to it.
One of the very few times that people ever get close (ie, pixel peep) to a large print is for group photos with large numbers of people. In this case, the only reason such intense intrest occurs is because people want to identify themself in the photo, see how they look, etc.
If you want further validation of the above comments, just take a stroll in a nearby shoppping mall. Take note of all the 4 - 6 foot high photos of models that are in the windows of many stores selling fashionable clothing, shoes, etc.. When you approach these photos closely and examine them carefully, you will see that almost every one of these images looks horrible -- they are almost always obviously out of focus, grainy, etc.. However, stand back for 10 minutes, be a fly on the wall, and just observe how ordinary shoppers view these posters. I doubt you will see a single person look at it from closer than several feet away.
Although there are exceptions to this general behavior, IMHO, in your case, no one will care an iota that the little flakes in your design are a bit rough around their edges, LOL.
That being said, there are ways to clean them up a bit without a huge amount of work, and I'm sure other members will respond with their suggestions.
Cheers,
Tom M
PS - I see Gedstar was writing as the same time as me. Yup, Image Trace in Adobe Illustator is exactly what I would have recommended, as well.
