Will I ruin my Cat if I keep driving?
 

I have a 1988 300 SEL with a check engine light on. Car is driving fine. Diagnostic code tells me it is number four, the Mass Air Filter. I don't need to pass somg for another year. Since the car is running fine I was thinking about just waiting until right before my smog to fix the AMF. My only concern was that it might clog up the cats. If this is a risk, I'd rather just fix it now. Let me know what you think.

On California version cars with that fuel system the computer will still function with a air-flow problem..not quite as effecient but still good. It will select a known good reading from previous info...that is called a FOM (fixed operation mode)