The battery is good and just been replaced 6 months ago. I inspected all pipe connections to check for any leaks and there is none. Including throttle body connections.
The RPM changes when pressing brake peddle only if engine is cold, which is normal I guess. There isn't much variation when it's on operating temperature.
When I turn on the AC, the car vibrates heavily for few moments before stabilising, which I suppose happens due to drop in RPM momentarily. These changes in vacuum pressure could be due to faulty PCV valve which I am not able to locate on 1KR-FE.
BTW the Brake Oil container is about 2-3 mm above MAX line. Can it cause extra pressure in brake booster/Master cylinder? I never topped it off ever. I suspect I may need to bleed the brake system but don't know how to do it properly and I don't trust local mechanics with something as vital as brakes.
( In my testing, when the AC is on, the vacuum pressure is not equalising when the peddle is pressed all the way. E.g. when you press the peddle all the way, it stops and locks in it's place before it should, about 1 inch earlier than normal and doesn't go soft at all. But when AC is off, it stops at some point but gradually goes soft until it reaches the limit.)
