Recap- Auto LS, car squeaks sometimes when I brake, not loud though. 2 days ago, at stop light with foot on brake pedal, pedal drecreased pressure and sank down, therefore car moved forward alittle, stepped on brake again and it braked fine. It happened a few times that day.
Other's comments--People say it's the master cylinder, or try to bleed the brake lines.
Today I drove it from 5-7 mins around the area, Braking pressure is fine, but still hear squeaking sometimes here and there. Why didn't the brake pedal's pressure decrease? could it be that I didnt' drive it long enough therefore that it isn't hot enough?

 

you have an air bubble in the brake lines somewhere.......need to bleed brakes. that is why you lost pressure.

The brakes are squeaking because they may be worn to the "warning" point. Check the pad thickness. If the pads are fine get brake quieting lube from pep boys and follow directions.

 

how do I check for thickness? what is normal?

 

as explained previously in your part 1 thread.

you have worn pads i think.

jack car up, take off the front left wheel, look at the thickness of the pads that sit either side of the disc and check the thickness against the service manual data.

replace if they are outside specs.

ALSO as explained previously the pads have a thing that makes them squeal when worn out...

if this is beyond your capacity - take it to a dealer and tell 'em your brakes are squealing and it doesnt stop so good.

t..

PS teh reason your peddle sunk to the floor is because the pads are worn, when they heat up the brake fluid boils and loses its viscosity and pressure...