Idle air control is off and RPM's are low. How do I fix?

The code is P0506

So , you re-installed the IAC , cleared the code(s) with a scan tool , and then you got P0506? First I don't see any parts listing for an IAC , Second the code is for low idle speed detected , not any particular part. check for air leaks between the mass air flow meter and throttle body housing. Then thoroughly inspect the mass air flow for dust/debris , PCV system clean, check and clean throttle body. Worst case , may save money in the long run (over guesses) , have it scanned by a shop $$ --like I said , it may end up less expensive AND less aggravating in the long run. good luck.