[seanc]

You've got different problems here:

a plastic plating basket I made with copper wire laced through the holes in the plastic on the bottom and 1" up the sides to provide continuity.

Your basket design won't work. The parts are in what's called "anode shadow". Most of the current is going to your coopper wire laced up the sides, and very little gets to the parts, so they're not plating properly.

I've tried the basket, and other methods. All have been failures for one reason or another.

Read the stick post: Best way to prep & plate nuts & bolts

3 second dip in 5% muratic rinsed and into black chromate solution

Use only sulphuric acid for black chromate parts.

the solution turned cloudy and eventually went from black chromate to a bronze color

Black chromate is extremely sensitive to contamination. Anything you put into the chromate solution must be rinsed absolutely clean.

Muriatic acid drag-out is bad for it. Black chromate is sulphuric acid based.

If you drag ANY electrolyte solution into the black chromate, the chromate bonds to the free zinc ions. Once bonded, those chromate molecules are used up forever.

If you see any milky streaks developing in the chromate when you immerse the parts, then they are not rinsed well enough. The more often you get milky streaks, the less effective the chromate becomes.

If the entire chromate solution has turned "milky coffee" color, it is shot! If your parts won't get beyond the "bronze" color, the chromate is all used up.

Sean