rpms, gas mileage
 

i have a 1998 C 230 (naturally aspirated), every now and then when i come to a stop the rpm's dip a little, not as bad as it did before i changed my mass airflow sensor and some other stuff. still, my gas mileage is bad and i'm not sure what is causing it. also when i turn on my a/c the rpm's will dip and go back up. once the a/c is running it is fine. i just had the a/c compressor replaced. Any ideas on what the issue is?

Check your air pump