Originally Posted by acid1216
I just know that since I've used that stuff I've had no idling problems (cross my fingers)
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If you need to put in premium gas to stop a problem you need to take care of the problem. The car is designed for 87 and will not perform as well on higher grades. Have you tried fuel system cleaners, seafoam, cleaning the egr ports?
As for the light, it can be diagnosed by yourself by 'jumping' the data connector as described in the FAQ