Gravel roads throw up a great deal of grit. The old lube was likely gummy enough to hold the grit in suspension, at least enough to muffle the sounds that you're now hearing. Cleaning the chain freed the grit but didn't remove it.
If it were me, I wouldn't waste time trying to clean the chain again. You're unlikely to get all of the grit out.
Different people have different approaches, including using wax and crock pots, but I've found that what works for me is to install a new chain, run it through a cloth after every ride or so, and then relube when it needs it.