i own a 2005 mazda rx-8 it has roughly 40k miles i have had a new problem with my car. once my car warms up and i drive it around for awhile around town or i drive to work when i go into neutral my car will start reving a little bit it happens completely random, sometimes it will happen sometimes it won't. the revs are usually low around 2 to 3k rpms but occasionally it has gone up to 4k rpms. i was worried because i have just recently around 6k miles ago but i just recently put a new clutch and flywheel but i doubt that is the problem.
also my car is manual transmission
if anyone has ever had this problem or has heard of it could you let me know thanks.

 

When was the last time you changed plugs/wires/coils?

 

sounds like a TPS problem or could also be the throttle body.

 

You think the Tire Pressure Monitoring System is causing his RPM's to fluctuate?

 

Jason said TPS not TPMS....

Throttle Position Sensor

 

I stand corrected