Okay, got it thanks.
First, I would check the rod under the brake pedal to be sure it is not sticking and allowing the brake pedal to return.
Then, we look at the booster. does it have vacuum to the booster with the engine running? if it does not, check the hose back to the manifold for being broken or not connected.. if it does, then it could be a bad booster.
Next is the master cylinder. is the fluid level correct and no visible leaks in the system? this sounds more like your issue. it could be bad seals inside the cylinder not holding pressure when you push the pedal.
https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder
when was the last time you changed the brake fluid? it should be done every 50,000 miles.
https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system
Roy
Friday, December 28th, 2018 AT 7:41 AM