ok so its a 92 and when i slam on brakes i can hear water sloshin around it almost sounds like its in the floor but im not sure. is this problem common and what can i do to solve it

 

Its somewhat common. Its in the rocker panels. I'll let someone else post who can give you the details.

 

Yup, your rocker panel is full of water. Happens to me because my rain rail is totally screwed. There are two drains built into the pinch seem on the miata, and they clog really easily. A lot of people take a drill and drill these drains larger.

 

I just poke the holes with a hanger it has never happened again. BTW the holes are located towards the front of the rails, where you would put jackstands.

 

and the rear^^^

 

In the rear there are hoses right in front of the tires those have not clog.

 

No these are different holes, on the pinch seem rail. Please understand.