Low RPM (hit the gas all the way down)
 

I need help
I have 05 RX8 RED
I started notice when i pulled the car out of the garage and drove out.
the car can't not speed up and it's take time to much to catch up the traffic.
5000 RPM when hit the gas all the way down.
top speed 68 MPH can't go faster the engine is noisy.
the automatic gear can't catch up.
high rmp sould sound like sharp and strong but mine is sound weak and kind of like cut of...

sounds like you're in limp mode (stops the engine from blowing up). This is usually caused by a clogged catalytic converter or bad o2 sensor. Are you not throwing a CEL? Searching the forum for 'Low RPM' should results in similar results and possibly other ideas.