Greetings. We recently purchased a 2000 5 Spd 4WD Highlander. During the first month we noticed the clutch pedal seemed pretty stiff but weren't particularly troubled by it. Then I was out of town and got a call from the family saying the clutch pedal was staying down and not returning when released. Fortunately everybody stayed calm and figured out how to pull it out by foot to get home.
After some research I deduced the clutch pedal bushing may be the issue. So I removed it and found this:
Pic taken after one end of spring manually removed
One side of Support Bracket with Spring removed:
Clutch Pedal where spring engages:
So we bought a new Support Bracket and all clutch pedal bushings and welded and machined the pedal to more closely match the original geometry. Then it was reinstalled and presto...the pedal would still stay down and now it was actually sinking down to the floor, not just hovering in the down position like before.
Looking through the PO's records it was clear some clutch work had recently been done including replacing the clutch slave and repairing the clutch master. This work was done by a Muffler shop.
We removed and disassembled the Master Cyl and found this:
(that Lil stainless plug doesn't belong in that socket)
And this:
(the seal shouldn't look like that and there's a pinhole in it)
Bought a Master Cyl rebuild kit (Toy pn 0431112110), rebuilt it, bled, and reinstalled less the stainless plug. All is well and operating less stiff now.
Note: I've seen the yotatech spring swap but it seems to make the pedal stiffer which would not be good for us and I just wasn't sold on the concept anyway.