KagyTee

Basically all the issues you mentioned in your initial post, injectors are reading flat -2.99, registering a misfire on cylinder 1 even after an injector and injector loom swap, also low MPG but I think my onboard computer is also reading wrong as when you work out the mpg, its much better than it actually displays.

Did you ever solve this? I have the same issue and I've changed injectors, injector loom, tandem pump, vacuum lines, fuel filter and still the same issue, injectors all read flat values like yours and misfire cylinder 1 even after the new ones.