Hello everybody. It's been a while since I've chimed in. I have a hunch about this but I want to run it by you guys before I buy any parts. I notice on my 96 Burb when I push the brake pedal while driving it is pretty hard and makes a loud whoosh sound. The engine rpm also drops and then raises again after I let off of the pedal. Also when traveling in reverse, I'll hit the brake and the rpm's will rise a little. I think its the original booster because it looks like crap being all rusty and bare from years of brake fluid being spilled on it. The truck has 220k on it. Thanks.