This vehicle has 235k miles. Still in relatively good shape. ABS and TCS lights come on frequently. Usually, not immediately, but after I drive just a few min. Many times it is after I hit some bumpy road. But, when I try to stop, it feels like the booster isn't working. Pedal is not allowed the travel to actuate the brakes unless a lot of pressure is used. Both front hubs have been replaced. New shocks and strut assemblies. I posted a 2007 Chevy Express that I own that is experiencing very similar issues. Is it a common Chevy issue?
GM had issues where the speed reluctor ring would get rusty and cause premature ABS activation, but I'm pretty sure they had that worked out before 2005 and it doesn't really sound like your issue since you changed the hubs.
You've got a lot of miles so I suspect it's the brake hydraulic system. tired worn out brake lines/master cylinder/abs pump ... that sort of thing.
