Sudden stops

My 1995 Corolla with 225,000 miles has lost power 3 times during the past 6 months while I was waiting at a traffic light. I have a new fuel pump, fuel filter, battery, alternator and spark plugs. When I told the mechanic that my foot used to automatically go lower on the brake pedal when I was at a stop light (as if saving gas while idling) and that it no longer does that, he gave me a strange look but could find nothing wrong with my car. It has done this again since he checked it out.

The brake pedal goes lower & lower towards the floor? If you pump the brake pedal, does it come back up?

Not a good sign for your brake master cylinder.

I’d be inclined to suspect the vacuum booster. With the engine off, pump the brakes a few times. The pedal should harden. Then, while holding your foot on the brake, turn the engine on. If you do not feel the pedal soften and some small amount of pedal sink, the booster is inoperative. If it’s inoerative due to a leak, that will also act as a vacuum leak to the engine and cause operating problems as well as making the brake pedal feel hard.

Post back.

I’ve had some cars where the brake pedal would sink a little while stopped when the AC compressor cycled off. The reason for the sinking was that the engine vacuum increased slightly with the reduced load. The increased vacuum made the brake power assist greater so that the same amount of foot force on the pedal resulted in it going a little lower.
That said…

What do you main by lost power? Do you mean any or all of the following?

  1. I lost electrical power, the radio and dash gauges shut down.
  2. The engine stalled and I had to restart it.
  3. The engine was still running but it would only accelerate very slowly from the stop.

Actually, the OP seems to say the reverse of that idea.
However, I am as puzzled as was his/her mechanic.
When the brake pedal goes closer to the floor, you save gas? That is a…novel theory.

Unfortunately, the OP’s post is extremely unclear.

Does “lost power” mean that the engine stalled?
That it idled at a lower speed?
That the car accelerated more slowly than usual?

Does it mean that electrical power was lost?

What does the position of the brake pedal have to do with this?

Are you asking about two different problems, or just one?

“It has done this again since he checked it out”–Does that mean that it “lost power” again, or does it refer to the higher brake pedal?

Mr. or Ms. Faithful really needs to make his/her post much clearer for us.
I’m sure that he/she thinks it is written clearly, but it most definitely is not.

Goldwing, MB, and tardis–

The OP states that, “my foot used to automatically go lower on the brake pedal when I was at a stop light”.

Re-read his/her extremely confusing post!

True enough. Perhaps the OP should see a doctor about that part of the problem.

What about the line that “It has done this again since he checked it out.” ?

I took this to mean that the brake pedal was sinking to the floor.

I saw that, VDC. That statement combined with the erratic idle is what caused me to think of the vacuum booster.