When slowly braking it the pedal goes to the floor slowly

Good afternoon,

If you have no leaks, then it does sound like a master cylinder.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Roy

NOTICE:
Release the vacuum from booster by depressing the brake pedal several times.

Then remove the brake master cylinder from brake booster.

1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL

2. DRAIN BRAKE FLUID

NOTICE:
Immediately wash off any brake fluid that comes into contact with any painted surfaces.

3. REMOVE CLUTCH RESERVOIR TUBE (for Manual Transmission)

(a)Disconnect the clutch reservoir tube from the reservoir.

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4. REMOVE BRAKE MASTER CYLINDER SUB-ASSEMBLY

(a)Disconnect the brake fluid level warning switch connector.

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(b)Using a union nut wrench, disconnect the 2 brake lines from the brake master cylinder sub-assembly.

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(c)Remove the 2 nuts, and then pull the brake master cylinder sub-assembly out of the brake booster.

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(d)Remove the O-ring from the brake master cylinder sub-assembly.

NOTICE:
* The master cylinder requires careful handling. Do not allow the master cylinder to receive any impact, such as from being dropped. Do not reuse a master cylinder that has been dropped.
* Do not strike or pinch the master cylinder piston, and do not cause any damage to the master cylinder piston by any other means.
* Release the vacuum from booster by depressing the brake pedal several times.
Then remove the brake master cylinder from brake booster.
* When installing the brake master cylinder sub-assembly onto the brake booster, or when removing the brake master cylinder sub-assembly from the brake booster, make sure that the brake master cylinder sub-assembly is kept horizontal or its tip faces downward (the piston faces upward) to prevent the master cylinder piston from falling off.
* Do not allow any foreign objects to contaminate the master cylinder piston. If a foreign object gets on the piston, remove it by using a piece of cloth and then apply an even layer of lithium soap based glycol grease around the circumference (sliding part) of the piston.
* Do not use any other type of grease or fluid.

You are welcome.

Always glad to help.

Roy