Intermittent (suspension?) rattle from left front on '01

TL;DR: I'm getting a rattling noise, intermittently, from somewhere in the left front of my '01. I replaced the left CV axle and that's not it. I did some inspection and prying around and I can't convince myself that it's the ball joint, sway bar, or sway bar links.

What could it be?

Caution: Long post ahead.

Long version:

History:

2001 with a bit over 250,000 miles on it. USA model, left-hand drive.

Both factory front struts were replaced (by a mechanic) with new KYB front struts at roughly 180,000 miles, but I don't know if he replaced the strut top mounts (triangular-ish plate with bearing) at that time.

New front tires (Generals, by a tire shop) at about 228,000 miles.

Both factory front sway bar links were replaced (by me) with Toyota parts at about 230,000 miles.

Characteristics:

A few hundred miles ago, I started to get a rattling noise that sounds like it's coming from the left front somewhere.

It doesn't always start as soon as I start driving. It can start "on its own", or after I go over a small or large bump in the road.

It can happen at anywhere from a few miles per hour on up.

Once the rattle starts, I can keep it going or even make it a bit louder by steering to the left. Steering straight keeps it going. Steering to the right quiets it down. These are all "normal lane change" amounts of steering, not "trying to keep in one lane" amounts of steering.

Once the rattle starts, it keeps happening if I'm driving uphill, on the level, or downhill.

Once the rattle starts, it keeps happening if I accelerate, coast, or slow down with the brakes. If I brake the car to a stop, the rattle stops around maybe 2 mph.

It's a fairly fast noise, maybe 2 or 3 Hz. It is a little bit correlated with road speed (rattles slightly faster if I drive faster); it's not correlated with engine speed.

I don't feel it in the steering wheel if it's not very loud. If it gets real loud, I feel it a little bit in the wheel.

It doesn't try to jerk the wheel out of my hands. It might cause a slight "shimmy" feel - as if the front end of the car is "wiggling" side to side - but I'm not 100% sure of this. I always feel like I still have control of the car.

The rattle is a little bit correlated with temperature. If the car has been sitting outside and it's been below 60 F (15.5 C) for a while, it's quiet as I first start driving it, but the rattle may start after I've driven it for a few miles. If it's over that temperature, the rattle seems to start sooner.

Sometimes the rattle doesn't happen at all. I drove it 8 miles this afternoon in 70 F (21 C) weather, and it was absolutely quiet the whole time.

What I've tried:

When the noise started, I jacked up the left front, took off the wheel, and inspected.

I noticed that the outboard CV joint boot was torn at the small diameter - right next to the clamp. It had been slinging grease on the top of the control arm, back of the wheel hub, etc. The inboard boot wasn't obviously torn.

I could move both sway bar link ends by grabbing them with two fingers and turning them. (The old ones that I replaced a few years ago were too stiff for that).

The outboard end of the sway bar itself is kind of rusty - from a few inches outboard of its rubber mounting bushing, to an inch or two before the end where the link bolts on. I looked it over and it's not rusted through, and I didn't see any major cracks, but I might have missed one.

I couldn't make any noises or play happen by grabbing the spring with both hands and trying to turn it (like steering the car), or by pushing inboard or pulling outboard on the spring. This was with the suspension at full droop.

The brake-caliper-to-bracket and bracket-to-hub bolts were torqued correctly.

The strut-to-hub bolts were torqued correctly.

The ball joint nuts and bolt (bottom side) were torqued correctly. The cotter pin was present in the tie rod end nut.

I tried prying between the lower control arm and the hub with a pry bar, and I didn't notice any movement in the ball joint.

The bolts that hold the sway bar bushings down to the subframe are at least present and not totally loose - I couldn't get the torque wrench on them, but I got a regular ratchet and socket on them, gave a good twist, and they didn't move.

I also put the left front wheel+tire back on, put one end of a five-foot (1.5 meter) 2x4 on the ground a few inches inboard of the tire, pulled up on the outboard end of the 2x4, and I didn't notice any movement in the ball joint.

Finally, I jacked up the right front, took that wheel off, and took a look around. It passed all of the same tests.

The right side also had a torn outboard CV joint boot, at the small diameter. It had also been slinging grease, but maybe not as much as the left side. The inboard boot did not appear to be torn.

I also noticed some heavier tread wear on the outboard edge of the right front tire - about 22,000 miles on it.

Changes that didn't fix it:

Because of the torn CV joint boot, the grease, and the dependency on which way I was steering, I decided to try replacing the (factory) left CV axle complete. I got a new complete axle from NAPA, and after some travail getting the big nut on the end of the axle loose, I got the old one out and the new one in. In doing that, one of the two ball joint nuts stripped out, so I replaced both nuts with "generic" metric nuts from the car parts store.

Unfortunately, the new axle didn't seem to change the rattle much.

Possible actions:

The place on the transmission where the axles connect is closer to the driver's side of the car, so I'm trying to convince myself that it could be a problem with the inboard CV joint on the right axle. I have a new replacement axle for that side, but I haven't installed it yet. I feel like the noise might be coming from further outboard than that, though.

I am also suspicious of the strut top mount on the driver's side. It appears to have a ball bearing in it, and it has occasionally made noise when turning at low speeds (like in a parking lot) before. Maybe it has worn enough to let the strut assembly move either up-down or inboard-outboard when driving, and that's the noise I hear. I will probably at least take the wipers off so I can check the three little mounting nuts, and the big nut that holds it
to the strut.

Go nuts and replace the lower control arm, ball joint, sway bar link, strut top bushing, and maybe the whole strut and the wheel bearing.

I'm willing to listen to any other ideas.

Thanks!