Hello Everyone,
I have a 2005 Silverado 2500hd with just over 300K miles and brake issues.

somewhere along the line (150-250k) the brake pedal seemed to be getting lower and lower. Then the booster failed. I thought great, now I know what was causing it. Changed the booster with a unit from autozone. Learned that was a big mistake the pedal was now lower than ever but, I had brakes again. After living with the low pedal for about a year I did some research and found out that a replacement from NAPA would be a lot better. I changed the Booster, changed fluid, went lock to lock, and bleed the system. The pedal is better but not like it used to be. It does engage the brakes as soon as you press down but seems to be weak. To me it seems like the back brakes are doing most of the work. back rims have a lot of dust compaired to almost none up front. I should say, I installed some of the highest rated pads on the forums (front & back) when I did the booster.
I can't seem to find any post with a fix or explaination for this issue. Someone told me that the rubber Brake Lines up front could be bad. Sounds a little far reaching to me...

Thank you for any help!