Picked up a used Alex duetto v1 in great condition cosmetically. Pulled a shot and tastes super sour. Tried changing the grind settings and no difference, longer shots yield more bitter but still sour shots. The pid was set to 94. I read somewhere that these machines have a 10 degree difference and the pid is displaying the brew boiler temp without accounting for the difference at the group. Is that the case with this machine? Do I need to adjust it 10 degrees higher to get the right brewing temp?

I already tried it by the way and it still tastes sour. Any ideas how to address this? I'm gonna use the same grind settings and pull a shot with my old machine and see if that tastes any better

Try raising the brew boiler temperature to 95˚C or 96˚C.
You might also try different beans, different origin, different roast level..