list o problems
 

okay first off i was timing my car and the 0-60 was 10 seconds
2nd problem everytime i brake i hear something rattle
and last of all everytime i drive my radiator light comes on

so what is my problem and how can i fix it

can anyonehelp me or tell me what my problem might be

low coolant or faulty low coolant indicator.

need more info...year/mileage....how did you time it? MT or AT? if MT, feather the clutch, or dump it....at which RPM...? if AT...did you just stomp it or power brake it? any power loss you've noticed? etc...

could be a lot of things man or a combination of things. be more specific so we can help

04 at rx8 with 54k miles
i timed it with a stopwatch
and i floored it to see
i bought car at 43k
when iclocked it it would be at about 7
now it is 10

First, 04 AT is your freaking problem, you dont even need to talk about speed anymore.

Second, rattle as in ? what ?

Third, your coolant light comes on and you dont know what it means? add some coolant hello? its not rocket science.

try power braking it (don't know if this is the actual term..its what I call it anyway). Step on the brake with your left foot and then step on the gas with your right while keeping your left on the brake. Keep the RPM's right at the point before it starts pushing thru the brake (even if it does that on the AT, I don't know). Then let off the brake and floor it at the same time. This way you are allowing the torque to build up before you stomp on it. Bet you will lower your times.

also you may need to have your coils/plugs changed as well given that mileage if you already haven't. GL

Some people really don't know....give the guy a break. He will learn.

1) you have a 4AT so go figure.... some common power loss things to check, carbon build up(seafoam), coils, cat

2) i dunno

3) the sensor is known to be faulty. it is built into the overflow tank, so you can have the whole thing replaced just to have it fail again at some point. OR you can just unplug the sensor as long as your willing to keep a good eye on coolant levels/temps.... search for a thread on it it has pics of unplugging the sensor

how do you check coolant level and temperatures

Please take the car to the dealer, It seems to me that you have no mechanical ability and would only make matters worse if you were to touch something under the hood.
I am sorry for being so blunt, but from your comments,, they speak for themselves.

+1...

was throwing a bone and giving benefit of doubt, but yeah. find a dealer you trust