Starting and idling problems

Wait up, you already proved my point, when you said; "and then when it dies I lose voltage." Would it be more correct to say;It doesn't die and then lose voltage; it loses voltage and then dies.
That's probably the ASD (Automatic Shut-Down) module.I can't say what it's responding to, unless it thinks the vehicle is being stolen (anti-theft program).The priming signal does not go through the module; it is a timed computer signal,activated every time the key is cycled.
Someone else smarter than me will be along shortly to help you. Hang in there. No need for a pressure gauge just yet.
In the meantime he will want to know what vehicle we're working on.