alfamonica-
Your gas mileage is about right. Check your spark plugs for a rough guess on your mixture. Another better way is to take it out on the road, run the RPMs up close to redline to burn off any gunk, then stop, shutoff the engine, and check the spark plugs for color. They should be a tan color. If they're black and sooty, then you may be running too rich. Before you start adjusting the fuel shutoff solenoid, however, you need to do some serious study on the SPICA system. Pat's book is terrific, but you should also get Wes Ingram's SPICA book. It's excellent. He also has a web site:
www.wesingram.com
An Alfa engine will still run pretty well with a far-out-of-adjustment FI pump. When you do a tuneup, however, you want to go through it VERY methodically. One adjustment in one place can affect another later. Do it "by the numbers." Generally there are a lot of SPICA Alfa's running (pretty well) with too-rich of mixtures.