1981 Eldorado Runs Rough - Help!

[jimkf]

I have an 81 Eldorado that has 39K original miles on it. I retrieved it from 15 years in storage and after changing the fluids, filters, plugs, wires, cap and rotor, it started right up. The problem is that it runs rough and acts like it's flooding or not getting enough air. The fuel economy indicator says I'm getting 8.8 mpg, which is less than half of what my 83 Seville got around town. I checked the trouble code and it displays '30', idle speed circuit. Indeed, the idle is sometimes very high, but I don't think it's the real culprit. Could it be the map sensor? Any thoughts are appreciated!