97 Limited Hard Brake Pedal, when Stomping on Brakes.

Hello, my trusty 97 Limited Automatic with 250K has a weird braking issue.
If I try to slam on the brakes, the pedal is very hard, and the 4runner will slow down and does not stop as quick as I would like, I can not Lock up the brakes.

If I do the same thing, but press slowly on the brake pedal, there is not as much pressure on the pedal and I can slow / stop much sooner. I have no trouble stopping if I do it slowly, it's just if I slam down on the brake pedal it take longer for the brakes to engage.

Last winter when it was below 15 degrees, when first moving the car, like backing up, I had to be very careful to step on the brakes very slowly.
I did replace the brake booster check valve and that seemed to help.

I have owned the 4runner for the last 8 years and 70K. I do all the maintenance myself. Brakes, timing belt, valve cover gasket, radiator, electrical....

I rebuilt the rear brakes a few years ago including replacing the parking brake hardware.
Just replaced front driver brake pads (took two hours because the caliper pin was stuck).

And suggestions would be welcome.

Thank you.
-andy

 

This seems to indicate a brake booster issue. If the pedal is hard, you aren't getting the assistance applying force to the hydraulic system from the booster. Likely a bad vacuum seal or a small leak since it does help during slower application. Lots of people chase brake issues by replacing the booster and it's never the problem. In your case, it sounds like it is.