@MadamaDemonSlayer why are you necroing something from several months ago? It's already been determined that this particular case is a lost cause due to...
- a lack of control over the environment (the OP lives in a rural area that has constant machinery running in the background)
- a cheap, LQ mic that's unsuitable for vocalsynth usage (not by choice, but it's probably all they have; the OP hasn't returned to say whether or not this has been resolved)
There's nothing the OP can do about this situation except try to relocate to a more suitable recording area and invest in a mic that will be better suited for recording UTAU. In the meantime, it's been suggested that they use the mic they have now to practice different recording styles, etc.
Post processing in the wrong hands tends to make a bad situation worse and it's generally a time waster to try to fix LQ output. UTAU is very sensitive to what's happening in a bank's given samples: bad quality in = bad quality out.