pplusent

I am posting this due to this problem that hounded my 4runner for several months and feel the fix may be helpful to some one else.
My 93 3.0 had an issue with lack of power and had a hard time getting through the smog test due to high NOX levels.
It acted like a vacuum leak, but no leaks where found. All hoses were replaced and all vacuum devices were tested and it continued to be a problem.
Eventually I started to notice the brakes were getting slightly hard, so I retested the brake booster and it failed. Once replaced the power and NOX issue went away and it ran great.
Even though I had tested the booster before and it passed, it was still leaking.
So if your having a similar issue then this would be a place to look. Since the failure I have been changing a lot of boosters that people have brought to me for repair. They also seem to be all in this model year range. Maybe the life expectancy of the brake boosters is right around 24 to 25 years.
I hope this helps some one out there!!!