This story is long and screwed up beyond all recognition.

I end up with an 01 Camry XLE. Traction Control, ABS, Front and Rear Calipers.
It has issues, and I fix them all. With regards to the brakes, I rebuild the rear brake shoe assembly, double flare bad brake line, replace 3 out of 4 calipers, and 3 of 4 caliper hoses. Soft Brake problems-- Master Cylinder is brand new, bought it like that. I replace the Master Cylinder. Good used OEM Master. Get good brake pressure, but I have a new problem: brakes are now locking up intermittently, generally after a short drive.

My mechanic has me replace ABS pump, the proportioning valve, and then the master cylinder again, this time with a new one. Spongy brake problems return immediately. I do this with 5-6 master cylinders until I decide to try an ASIN stamped OEM variety, new. Works great, I have brake pressure now. Still not hard like I want, but I've driven worse. Traction light is on, but the Engine Light being on can cause that, and it is indeed on, bad knock sensor, not doing intake job until I figure this out. Reasonable, right?

Brakes are still locking up intermittently. Mechanic says the codes on the ABS module say Front Right, Front Left, and Rear Left is locking up, or something along those lines. I swap out the ABS pump one more time. Mind you, this is mostly sweat on MY brow.

Today, I adjusted the clearance on the brake booster to minimum threading. Nothing. Booster holds vacuum.

The symptoms of the lockup are as follows: Works perfectly on startup. Drive for 5-10 minutes, maybe less, and eventually, the car begins bogging down, requiring far too many rpms to get to speed or shift. Once you "break" free, it seems to be okay, but you have to overcome the sheer resistance of the brakes locking up.

 

Locking up as in to the point of skidding?

Try to determine what wheel brake sare locking up by actually checking physically..

Check the brake flex hoses. The internal section can fail and not allow fluid to flow back.

In case the brake booster is the issue remove the vacuum hose to the booster to turn it off.

Toyota appears to have zero clearance for the master cylinder rod.

Is the brake fluid OK, no water.

Make sure the caliber pistons can move freely to retract.

 

Thanks for responding.

Not to the point of skidding, just where I have to break free of the tension to start gaining real speeds. It feels like a transmission issue, but it's not, it's the brakes apparently.

All fluid is brand new, completely fresh and water free. All calipers have been replaced save one, and one caliper can't make this problem. Ditto the brake hose to it.

The Abs module is reading codes for it, it seems like a complex diagnostic issue, but it's not the Abs module itself as that has been replaced twice and the problem persists.

 

You sure its the brakes? A torque converter or trans can start to slip causing what might be thought as a brake problem.

Might do the following.

Find a long road with little traffic where you can experiment and if needed pull over and stop quickly.

Get up to speed, let the gas off, shift into neutral and get the feel of the car slowing down. Drive until the brakes start to bind and repeat this to determine if the car now slows down faster due to the brakes. Your trying to determine if its the brakes or something else.

When the brakes bind, stop car on side of road and feel brake hubs for excess brake heat. An infrared temp sensor may also work. If you can jack up one tire at time to determine if it binds during rotation.

As stated previously you can disconnect the vacuum line to brake booster to turn it off. You can also pull the ABS fuse.

If not done already try backing off on the emergency brake shoe adjustment in case the shoes are binding with the drums.