High Idle Issue

I've been noticing over the past couple weeks that on occasion my car has been idling higher. My car usually idles around 8-900rpm...with the air on it's around 1100 but recently I've seen my car idle without the air as high as 1400rpm. The car was retuned months ago and haven't had any issues up until a couple weeks ago. Is it possible it can me a mechanical issue instead of it being in the tune? Any ideas as to where I can start to look? Thanks for any help.

My mods are extensive...CAI, Accufab TB/Plenum, Intake Spacer, Cams, Ported Heads, Pulleys, Headers, Catback, Gears, Tune By Diablosport. the IAC was replaced a few months ago when the custom tune was done at Diablosport, this problem only showed itself over the last couple weeks.