[75chev4x4]

75 Chevy k20. For the last month or so my brake light on the dash has come on randomly while hitting the brakes. In the last week I have replaced the brake light switch bleed the brakes with a power bleeder and replaced my check valve on the booster. The problem has gotten worse. Even before doing any of this work when cold the brake pedal would got further to the floor and I thought this was because the choke was on and it would go away once warmed up. Now every third time I hit the brakes or so the pedal will do this and that red brake light comes on. To me it doesn't feel like air in the lines but like no power brakes? So now this red light is coming on when I brake not evertime but a lot. I read about the pin on the proportioning valve and it makes no sense to me and I'm not sure that this is even what is causing my problem. I rebleed the brakes again about half hour ago and still same thing. Was supposed to us my truck for camping Monday but I don't wanna risk it with this issue. Anyone have some advice on this?