At 38F and 1.5 volumes, yes, it is under 1 psi. Setting it to 5 psi for half of the time doesn't actually make sense to me, and I think your beer is under carbonated to start. The reason it starts to pour correctly after you leave it hooked up for a while is that the CO2 level comes up to 2 volumes (6 psi at 38F). I would set it to 6 psi to begin with and carbonate your keg to 2 volumes. It should pour right every time when you move it to nitro at 24 psi for serving.