When I give my car the gas or stop I hear a swooshing of water coming from under the dashboard

Vacuum leak, inspect all vacuum hoses behind your dash, this will require some partial removal of your dashboad.

I had the water sound and it was the center console a/c. If you look under the console on the outside of the vehicle , best crawling under the drivers side. You will see a little rubber boot protruding from he sheet metal, almost center of the vehicle. That's the drain for the condenser in the console. Flick it a few times as trash will clog it up and will not drain properly.

This could be a simple air pocket. Run vehicle with radiator cap off. You will see air bubbles come up. Usually the fan will cycle on and off 3 times and both upper and lower radiator hoses hot. Remember to turn off all heat ac and defrost as this can prematurely cycle cooling fans. This will get all air out. This is also the way to do it anytime coolant is needed and or cooling repairs are done.

I had a similar swooshing sound under the vehicle on a '90 4 runner. Turned out to be water trapped in the running boards. Removed rubber plugs, water drained out, swooshing was gone.

If the swooshing sound is up in the dash area..and you have not lost any coolant.. chances are you have a plugged AC/Defroster system drain hose.

On a hot humid summer day when folks are running the AC you may have noticed puddles of water under your car and others. This is the excess moisture being pulled out of the passenger compartment. It collects and drips out of the drain under the car.

You probably don't have that puddle forming anymore.. the drain is clogged. Next time you have it in for an oil change at a decent shop.. have them locate that hose..give it a blast of air.. to unclog it.. and drain that water..

If the sound is coming from somewhere else.. best to locate it and drain it.. or clean the drain holes..doors etc..

Best of luck!

OK, a hard brake pedal is a good thing, in general. But, if the booster is not giving full power due to a vacuum leak, then stopping performance will be diminished due to the lack of vacuum assist.

Make sure the booster is holding vacuum by shutting off the car, locating the booster under the hood at the firewall, between the master cylinder and the firewall.

After a few minutes, remove the check valve from the booster by pulling it out. You should hear a loud swoosh of air going into the booster. If not, the booster may have a leak in it, or the check valve is not working.

Good luck on diagnosing the hard braking problem.

get the sunroof drains blown out with a high pressure air hose.chances are there blocked.

if it was the speedometer cable, the speedometer wouldn't work

You have an air leak in your coolant pipes under the dash.
There is air in the system.
When the engine is off the coolant is dripping onto the carpet.

heated water goes to your heater core under your dash..though you shouldnt be hearing it usually..be sure water level is up at radiator overflow reservoir and pay attention in cabin of any sweet smell of coolant indicating a failing /leaking heater core....look for damp carpet on passenger front area if suspicious