Since it sounds like something is restricting the flow of gas, the issue could be with either regulator (or a problem with the line coming from the tank - did you check for kinks or sharp bends?) The one at the tank is a high pressure regulator that steps things down, and the one at the stove is a low pressure regulator that drops it a second time to feed the stove with the proper pressure.
Based on your photo, the stove regulator looks properly set according to the manual (note the LP marking showing in the plug). It may be difficult to confirm it is operating properly without a pressure gauge. Are there markings on the regulator at your tank? I guess we also should have asked earlier if this stove worked properly in this setting in the past, or if this is a new-to-you installation. If the tank regulator doesn't drop the pressure enough for the stove regulator, that might cause an issue.