tfdcruiser

Okay that title best describes my problem. I have already changed my M/C with a new one after my 98 12v's brakes first started acting up. Initially the pedal would intermittently go a little soft and travel farther than usual and the abs and brake light would come on. If I turned the truck off and then back on the lights would go out and about fifty percent of the time the brakes would feel fine and the lights would not come back. But now it is happening pretty consistently with the softer longer travel then the lights come on, never fully losing brake power though, not yet anyway. Well I had a friend work the brakes while I removed the rubber cover on the proportioning valve and the pin moves up and down with the pushing of the brake pedal. Now does this mean that the proportioning valve is bad or is there a possible problem elsewhere in the system like a soft line. BTW there are no visible leaks anywhere. I do have a front brake line that shows some abrasion but not leaking and I can feel a slight pulsing in the line when the brakes are stepped on by my friend. Please chime in DTR you guys have never failed me. Thanks, don