Originally Posted by JimN
How did you determine the parts being faulty? If you tested them, fine, but if you just started replacing parts in hopes of finding the solution, it's going to be an expensive, frustrating journey. Buy a manual- it has testing procedures for the various systems, each in their own section. If you know someone who has serviced GM engines, ask them for their help.
Did you check fuel pressure, yet? What's the voltage when it's running? These need to be at the correct voltage in order to operate properly.
JimN, thanks for your help so far! Testing parts now so trying to find fault before replacing parts. Know the idle motor is shot as it does no move with any power on or off. It stays closed permanently. The rest seem ok from the tests I have just done.