My rpm drops around 300 when releasing the throttle then goes back up to what it should be.

Say im cruising at 2300 rpm. I lightly tap the throttle, I release the throttle, rpm on tach drops to 2k for a second then jumps back to 2300.

This happens no matter how light or hard I press the pedal. Is this normal for these cars? The car accelerates fine.

 

Check your rad fluid for air, air filter, fuel filter, fuel pump and injectors.

How many miles and when was the last major service?

 

Air filter is new. I thought the fuel filter is inside the pump? 60k miles.

Why would air bubbles effect it? I have noticed that the coolant temp is a little below the halfway mark.

 

Sounds like a hesitation. Trying cleaning the mass air flow sensor

 

What if his MAF sensor is going bad?

 

It's not impossible, that can be checked and monitored with proper scan tool equipment.

However usually when they go bad they usually fail completely. With the symptoms he listed it sounds like it is still functioning.

 

Right now cruising gives me a 16:1 AFR. Something seems off.

The MAF sensor has been getting wet with oil. I recently put in a catch can. Last time I cleaned the MAF sensor, the car idled at 17:1 which seems very lean. Right now it idles at 16:1.