Austin99z28

Hello. I own a 99 z28 and the check engine light displays a high idle code. The car idles at about 900-1100 rpm in park and usually around 650-800 in gear. The car has a fast lsx 102 intake, pacesetter long tubes, possible injectors, 3" exhaust no cats into ORY then to magnaflow. Just today I replaced the throttle body gasket, the car has stock throttle body and mass airflow sensor. Previously when trying to figure out the issue for the high idle, I noticed the throttle body gasket was at the end of its life and was worn and had flat spots so I replaced it. Highly noticeable visual difference. I installed it back on the car then proceeded with a PCM idle learn procedure. After all the work, it still runs the same. Any ideas for why it idles as high as it does? I don't think it will cause damage, I just don't like seeing the light come on and have codes. Want to fix the problem and not delete it. Thanks!