It's fair to say a carburetor might get you home even though its not happy, however an EFI system will probably shut down.
If none of the points raised by Paul are at fault there are several more culprits to consider, fuel pressure at idle and under load, fuel plumbing configuration (return and returnless), type of lines (hose or hard line), injector sizing, fuel filters inline or in tank, routing of wiring harness and condition of charging system and so on.
We installed 8Stack EFI systems on Ford Racing 347 Crate Motors a dozen years ago in CAV GT40s, before self learning software was available. Lots of time on the chassis dyno, manually adjusting the math tables, chasing down rabbit holes of setup and mechanical issues. Wasn't fun or cheap but everything worked out great.
The four barrel EFI systems available today depend on every component ahead of and behind them working properly in order for them to do so as well. They're not quite the "plug and play" type of installation you can do in three or four hours the manufacturers would like you to believe.
We put a self learning MSD 4 Barrel EFI system on an ex drag raced Cobra powered by a 351 Windsor. Installation included fitting the high pressure fuel pump in tank, oxygen sensor well way from the collector, changed the intake manifold, fuel rail resonator (retunless system), new distributor and made sure of no leaks.
The engine fired right up on the initial settings provided based on the known engine specs. The fuel economy nearly tripled, exhaust fumes dramatically reduced, overall drive-ability much improved, however over cammed according to MSD tech support regarding higher RPM.
I wouldn't hesitate to put one of these 4 barrel EFI systems on a mild engine keeping in mind the rest of the mods required.
Cheers
Ian