Many vehicles employ a vacuum brake booster in order to provide additional power to the braking system. It's designed to provide consistent flow of hydraulic brake fluid to the brake master cylinder while increasing brake pressure and helping heavy vehicles stop more easily. This component is common on a variety of consumer cars, trucks and SUVs. From time to time, the vacuum brake booster is susceptible to damage or typical wear and tear. This includes the brake booster check valve. The check valve is designed to suck out air that is trapped in the brake booster without letting additional air enter the cylinder.
A oil change won't help that problem you should have a shop scan it to see if there's any other problems. Js answered 4 years ago. If your Trailblazer has over , miles on it you're due for a tune up. Check your air filter. Is it dirty?