Clarification question: When you say low brake pedal, do you mean that when you put your foot on the brake pedal it doesn't feel firm right away, that the pedal travels a bit before firming up?
If it were my car I would consider changing the flexible brake lines. They are known to swell with age.
A quick test is to get someone to apply the brakes firmly with the engine running while holding one of these lines (such as a front one). Just a little swelling over the length of the tubing can translate into a large amount of pedal travel.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)