Did you perform a vacuum leak test using a cheap homemade smoke machine? Any false air getting into the vacuum side of the fuel injection system will cause idle and running issues.
Did you test the fuel injection system using a fuel pressure gauge to verify fuel pressure and control fuel pressure? A CIS fuel pressure gauge set will cost around $100 and is essential if you do all your own work. Do search for a thread on CIS fuel injection for dummies. It will provide all the info you will need to help test and isolate your issue.