Toyota Problems

You need to have the ABS system checked; it sounds like a dodgy wheel sensor or something similar.
 

Good news, you can buy the very same tyres to replace your worn-out ones. They are a popular tyre with Toyota owners because they wear so well and Dunlop continues to import them. Buying the same tyres also gives you the chance to cycle your current spare onto the vehicle and fit one of the new tyres to the spare wheel on the back. That way you won't end up with a useless spare that has been baked rock hard in the sun.

It's a problem with the engine/gearbox management computer and affected cars all over the world. We understand that Toyota redesigned the ECM to fix the problem, so go to a Toyota dealer and ask about a new ECM that has the fix. Don't replace it with another ECM of the same sort that it is currently in your car, that won't fix the problem.

I wouldn't be doing the fuel pump and injectors; it doesn't seem likely that that will solve the problem. I would be focusing on the drive side of the vehicle, I reckon it's a vehicle speed related problem, perhaps a wheel bearing.

It does seen unreasonable to have to remove the engine to fix an oil leak at the timing cover, I would take it somewhere else and get another quote. Oil leaks are not uncommon on Toyotas, as they are on other models, so I would doubt that you would win an argument that it wasn't wear-and tear. If the leak isn't a bad one then I would think you could carry on for some time before you needed to have it fixed.
 

There appears to have been little or no warning, which is odd. If it were short of oil I would have expected it to become noisy or hot before it gave up the ghost completely. On most gearboxes you can check the oil level, that's the best way to tell if you've got a problem.

You say the car had a poor service history when you bought it, and there was sludge under the filler cap. Both should have been warning to you that this car hasn't been well cared for; you are now paying the price. Sludge builds up in the oil galleries when the oil isn't regularly changed, and if let go long enough can cause blockages that can be fatal to an engine. It's rattling, using a lot of oil, and blowing a lot of black smoke, you should have it pulled down and inspected, and possibly rebuilt.
 

The only way to resolve a problem is to report it, first to the dealer, then to the carmaker if that doesn't solve it. After that it becomes difficult. My view is that there should be an industry ombudsman who can resolve issues between carmakers and their customers.
 

It seems to be a common problem with Toyota diesels, and one that doesn't have a fix. Others I know of have had the injectors replaced, only for the problem to come back a few months later. Go to a diesel engine specialist and get their advice.