...when i replace the stock ecu with apexi power FC the idle was unstable...when the car is cold it go up and down...when is normal is perfect, somethimes (temperature 90°C) it go to 3000 and go up and down...3000 2500 3000 25000, it's funny but not normal! what is the problem????

 

(1) You should be posting this on the PFC-ECU forum.
(2) A PFC forum search on this will result in many threads as this is one of the most common questions from PFC newbs.
(3)The most common reason for this is that the engine is either getting too much or too little idle air flow. Use the Air Adjust Screw on the throttle body to make this adjustment by opening or closing it in 1/2 turn increments until you fine the sweet spot.