I have an 06 2500hd crew cab. Lately I've noticed that when I hit the brake the pedal it feels spongey right before the truck comes to a stop, real low wheel speed.What could that be? Air getting in the system somehow? I haven't had any service on the brakes done recently, I dont know how it could have started. Any ideas? I talked to a buddy of mine who is a mechanic at a dealership (not chevy though) and said that he thinks it could be an ABS sensor going bad. After he said that it kinda make sense because the action I get from the brake pedal when it happens feels like the abs is kickin in. Any info would be greatly appreciated.