If it's a bosch based efi system it will probably run 3 bar fuel pressure and drop at pretty much 1:1 with the manifold pressure, so like 2.3 bar at idle.
Since you are running an aftermarket ECU you should be able to get away with just disconnecting the vacuum source from the regulator and running at fixed pressure and tune for that. A simple inline fuel gauge should do the job.
Are you using a wideband oxy sensor?
You were posting about it pulsing or something at idle? That is often an indication of your AFR being wrong so it swings between too rich and too lean
You also mentioned your temperature sensor was all over the place. Fueling changes significantly with temperature readings, so this could be the cause of your issues.