P0506
 

Hello, all.
Hoe do I fix this code? A mechanic I went to replaced the spark plugs, cleaned the carburetor and I cleaned the K&N engine and cabin filter. Tghey were dirty, I didn't clean them for a long time, totally forgot. Yet, the code is still on.
How do I fix it?

How does it idle?

The RPM drop a bit every 8-10 sec.

I would clean the throttle body and IAC.

The throttle body has been cleaned already. Will try the IAC.
Thank you very much.

They should have cleaned it at the same time.

I don't know if he did. Have to ask him. I don't like this mechanic but he is next door from m y work and I don't have time to go anywhere else, I work 6 days a week, 55 hrs.

grcauto made a good suggestion, clean the IAC.