I have a 94 SE with 88000 miles that up until 2 days ago has had a rather firm break pedal, now I can push it almost all the way down to the floor. I t doesn't appear the I have a brake fluid leak as the master cylinder is full and I get no indicators on the dash at all. Any ideas on where to look first?

Inspect your rear brake cylinders (just pull the wheels and drums) for buildup. This would indicate a slight leak, with dust collecting on the fluid. If you don't see any there, check the front (rear are most likely).

Nothing found? Bleed the brakes, starting with the furthest (right rear) from the master cylinder.