Toyota Repair: Toyota pickup idle problem, vacuum leak, 22r engine

Question
I have a 92 Toyota pickup 4 cyl, manual, 22r engine. The idle goes up and down only when brake pedal is pressed. can't find vacuum leak, and timing is fine. I don't know if brake booster is leaking or maybe it's idle control valve? When brake pedal is released, it idles fine.

Answer
If the vacuum hose from the manifold to the brake booster is not leaking then it's very possible that the brake booster has an internal leak. Disconnect the hose and plug it up and see if the idle remains steady, if so then again, I would say the brake booster is the problem.