My 2002 honda civic ex vtec 1.7L manual transmission is giving me the headache ot my life. For some months now been having this unusual RPM issue that wont leave for any reason.when the car is in idle mood and i press the gas pedal, the Rpm will not goes down to normal as it should .it would drop slowly and stop at 1000 and slowly goes down. My Idle air control valve is 2 weeks old from the dealer and i changed 2 before i baught the dealer one.no air in the coolant because i blead it several time.i checked for vacuum leak and found one in the brake booster and i replaced the booster but the problem still remains the same. I had these two codes, p1505 for pcv valve leakage and after replace the booster it never comes back.the other code is p0113 for IAT Sensor and i changed 3 sensor,cleaned the connector and put electrical grease on the connector since this code started showing up but somehow the issue still there. Anyone with some good honda experience can give some advice an what is my issue may be.