What you describe sounds very much like dirty wheels and dirty track.
The best track cleaning car I have found is a CMX Clean Machine from Tony's Trains filled with lacquer thinner.
The locomotive wheels have to be done separately by letting the wheels spin on a cloth soaked with track cleaner or rubbing alcohol.
A bright boy can supposedly scratch track and cause even more dirt problems if you press down too hard on it, and it soon gums up with dirt and just spreads it around instead of cleaning. A liquid cleaner, even something like mag wheel cleaner applied and then buffed off with a soft, clean cloth is better than a bright boy.
Don't use Goo Gone -- it leaves a sticky film on the rail and locomotive wheels that just attracts more dirt.
I have DCC on my HO layout. Until recently it has worked fine -- I have numerous power feeds throughout the layout. Over the weekend I noticed I am getting some power "brownouts" (trains stop running, lights go off, etc.) in some areas. How can that be fixed? Bright Boy on the tracks? Clean loco wheels? Etc. Any help would be appreciated.