the RPM is kind of slow 600-650 check engine light is on, trouble code is P0505

What is your question?

wich is the Idle control system, I bought the air idle control and when I instaled in the car the RPM went from 600-650 to 2,500. I let it run like 25 minutes and never went down to normal RPM about 800. I repleced again with the old one and came down to 600 again does any body has an idea why the new air idle control couse the RPM to rise to high?