I have about 6000 ( i travel a lot and despise airplane seats ) miles on my 2019 GMC SEIRRA DENALI 5.3 ( I love chrome lol ) . I've been experiencing a very troubling issue been to the dealership once already and had a hard time convincing them that something was wrong with the truck .Every time i drive for long periods of time or idle for 10+ mins when i shift from park to drive i cannot go faster than 5 mph without the rear brakes locking up. I do not know if this is some kind of limp mode or what . Contacted GM they work slower than molasses , idk what to do