1zz TB CEL?

[Black_griffin6]

Hey guys,

I installed the 1zz throttle body a while ago (probably a good 2 months ago). Now all of a sudden I keep getting a CEL with the code P0 505 (which has something to do with the idle).

I have no idea why this is happening, the only mods I did since then was some TRD upper strut mounts and TRD rollstopper AKA the TRD rear transmission mount.
I have noticed it's idling a little high whenever this happens, i've reset the ECU twice already and this is the third time i've got a CEL.

Any ideas as to why this is happening all of a sudden? It was fine for a long time up until recently.

EDIT: I should also note: The only other intake mods are a Weapon R secret weapon intake, and the air filter is still pretty clean. And engine mods are a pulley kit, DC header, and Mandrell bent cat back exhaust.