I have a '05 LT that just turned 50K miles. I'm not the original owner, but bought it in '07 with 10K miles in great condition and have babied it ever since. I've kept the brakes in good shape and have always had a very firm pedal...until about 3 months ago when I was on a 4-lane going about 70 and had to hit the brakes hard to avoid some traffic which had suddenly slowed. The ABS engaged and the tires chirped a bit, but I got stopped. Ever since, the pedal has been much softer with more travel. It's not horrible, but definitely doesn't have the stopping power it used to.

Any ideas on why the pedal is suddenly softer and how to fix it??

 

I'm not sure why they would be softer. Any leaks under the car possibly indicating a ruptured line??
Your safety is definitely worth a trip to a reputable shop for a full braking system check.

 

Have you checked the Brake Fluid level to see where it is? Make sure it is at the recommended level, don't over fill it. Then pump the brakes some and test it again.

 

Soft pedal could be air in the system. You might try bleeding.

 

This was going to be my suggestion. Maybe just get the whole system flushed if it never was.