You may have pressure but you dont' have volume. Have you had your water service replaced? I won't think 88 psi would need a pressure reducing valve but others have a stricter standard.
In buying a heater that will only supply two fixtures, think of all the money you will save by not having hot water . Oops, I see you're electric. Maybe you won't get to save any money over a gas tank heater .
My sarcasm must mean I have not changed over to the tankless heater concept yet. They do require some life style changes.