Getting lukewarm water out of single lever shower. I replaced everything, even the shut off valve. Still getting luke warm water. All other faucets get hot water, except washing machine. I am at my wits end. Any solutions?

Is it single handle shower faucet / newer model ?

Back to you / Milo

except washing machine

Close the hot at the washer and see what happens at the shower.

All newer single handle faucets have anti scald features. You can override by adjusting the stop ring under the faceplate. The manual for your model should show how to do it. Washer inlet could be plugged or your model only allows warm wash.