I have a 1998 Tacoma 4x4 with a 4 cyl standard transmission and lately I've noticed my brakes are "soft", and by that I mean I can push the pedal way way down. The brake fluid is within normal range and I can't find any leaking anywhere. The brake pads seem good also. This is jot my daily driver but rather is my hunting/fishing truck. Any ideas as to what may be the problem before I drop tons of $ on a mechanic?