My SUT starts up fine, It's just when I let it idle down, it dies. I replaced the clutch and springs, and that didn't fix it. I'm assuming it's the low speed needle because it revs up fine, and works great on top end...Should I lean it out or richen it up?

try leaning it.

Explain how exactly it dies, Don't just start leaning on it, that's not the solution to everything.
it might be too lean already.

Does it dies as soon as it comes to idle? or does it take a few seconds at idle? How many seconds?
does it sound like it getting rich and then dieing? Do you have fuel poring out the pipe after?

What the fuel/plug combo?

First check the plug, that the first thing to check when having any engine dieing problems
a fresh plug might be what the Dr. ordered
At least make sure the plug is good before you start plying with needles

It might be as simple as upping the idle RPM a little with the idle stop screw

You know, when he says it idles down, that sounds pretty rich in my book. I haven't known a lean setting to idle down and then die. I have known Lean engines to die as soon as you throttle up. But when idle, they will either not idle at all or idle very high.

Try leaning the engine slightly. Check the glow plug while you're at it.

Determining a tuning problem online is extremely difficult at best
Without actually seeing and hearing it is very hard.

You may be right, it may be rich, but without more info who knows

IMO, the plug is always the first thing to check.
Never play with needles until you know you have a good plug
And you have the right plug/engine/fuel combo.
Trying to tune an engine to a bad plug will really screw you up.