Does this look like normal idling rpms?
 

Here are 2 photos I took earlier. One shows my car's idling rpms in Drive and the other is in Neutral. Do these look right or are they too low? There is a small plastic nut on on the throttle cable by the gas pedal that I can adjust to make the idle go higher or lower. Just want to make sure this looks right.

My 300E used to idle around 500-550 smoothly. My V8 M116 idles about 50 rpm less than your picture in Drive, but around 950 in Park.

Idle speed on the gas engines is highly influenced by the amount of air making it into the manifold while idling....I dropped the in-Park RPM's on mine by almost 400 by just replacing all the rubber hoses!

Yours looks to be running normal/just fine. Does it idle smoothly?

This is just fine.

My 300e idles at 450rpm warm in drive...smooth as can be too. I'm not complaining.

If it were too low, adjusting the cable is not how you remedy the problem. Idle speed is electronically controlled and not mechanically adjustable. Mis-adjusting the cable would only result in poorer mileage and stalling.

Yes, I actually took out a little silver ball bearing and made my fuel mixture richer. I read that if fuel mixture is too lean it may cause the engine combustion temp to be too hot which can increase NOX, so I turned it clockwise to make it a bit richer. I do not have a duty cycle or a way to check %'s so I started the engine and slowly began turning it. The idle didn't seem to change much after I restarted engine, maybe slightly lower by a fraction of what it previously was and there is no erratic idling. I did notice that after doing the mixture adjustment I got 325 miles on 1 tank of gas, combo city and highway driving, but I normally average about 280-300. I haven't gotten any cel codes either. Maybe the engine was running leaning because I did notice that after smog my nox was higher than all other components and the cat was installed the same day as smog and engine was warmed up. here is link I used for fuel mixture BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT

you want the lowest idle for racing thru the corners,be careful to lean and you can melt the engine

Racing thru corners? Ha! I'm driving a Benz not a Civic, I prefer to drive. And yes, I made the mixture richer, not leaner, I suspected it was running leaning.

Please substantiate your claim.

melt the engine? I find that pretty hard to believe....