230/8,

I worked on those cars when almost new. Mileage of 13 miles per gal sounds about right. Mileage really improved when thy went to the lightweight alluminum block. Your new ingectors should be blue and not yellow. That car was designed to run on regular gas and not premium. You can't get a better plug than NGK. They've been my plug of choice for 30 years. You can't look at tailpipes anymore. The reformulated gas makes them all look sooty. In fact I believe it was the lead that used to make them look ashen grey. It's called D Jetronics, because D stands for Druck or pressure in German. The computer adjusts fuel by monitoring manifold pressure. The manifold pressure sensor mounted on your left fender well should compensate for the 3 inches less vacuum you are experiencing where you live. Someone else will have to answer your question about CO at higher speeds. Hope some of this info is helpful.

Peter

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