1.5hp mate carb issues

[Danderson]

I have an Evinrude mate 1.5hp. Not sure what year. It runs but not great, because it’s a direct drive and so low hp it doesn't really have an idle but it runs great at mid throttle. When I open it all the way up it surges. It hits max throttle and then putters out like it runs out of fuel and then revs up again before it can die and continues this cycle. I have tried turning the mixture screws and it has no response unless I take the high speed screw all the way out and then it runs great. Any ideas?