The last 500 miles or so I have driven the check engine light has been coming and going very frequently: four times on my last tank of gas, about 3 on this current tank. It stays on for various amounts of time, and turns off seemingly arbitrarily.

I've ignored it because anytime I've called the dealership to get it checked out the light turns off the night before my appointment :s.

The 'reduced performance' yellow light flashes on the dash every now and then. I say flash because the light will literally show yellow and the text will begin to show, but it never stays for more than a moment...

Has anyone heard of anything like this before?

 

Each time the fault light comes on, (plus the message), a fault code, (or codes), will be stored in memory. So really you need to have somebody read these off to see what might be happening.

Problems on cars never go away if ignored IMHO.

 

Agreed. The dealership suggests that I bring it in and get a body cleaning b/c apparently the Mass Airflow Sensor can get dirty and malfunction. It goes in Wednesday.