If you're not willing to "tune" a carb then that's not going to be the best choice. I believe you'd be better off finding the problem with your EFI or taking it to a shop and have them fix it.

You're describing a fuel supply issue and it seems the intermittent lean condition has been happening all along. If the pump is shutting off when you are driving the car I'd start there. The two most likely causes of the pump shutting off may be faulty wiring (and I'm including your power source in that) or a faulty pump. If you've verified all the wiring (including the ground -- and don't run a ground wire to aluminum) is good then you may want to hot wire the pump from a dedicated (and fused) circuit that you are sure will be constant hot while you perform another test drive. If the pump still drops out and nothing else is obvious it may be time to simply replace it and see if the problem persists.

I've never liked the idea that you power the EFI from the positive coil terminal -- don't know that this is a problem with your system but some systems don't like this power source. It's not the cleanest power but if the manufacturer's wiring diagram shows this as a point to pull power from that may not be a concern.