Thanks for the reply.
Tuneecu said I had 12.4 volts when I was using it.
Regarding the vacuum, I may have created the problem. When I first installed the denso injectors the retaining clips kept coming loose from the fuel supply resulting in the injectors sliding down into the throttle bodies. After three attempts to get them to stay in place I fitted some shims to the bottom of the injectors forcing them to stay seated in the fuel supply. I may have then created an air leak at the throttle bodies. How do I test for a vacuum leak? This all seems like a bit of a black art.