Greg,
If you are sure that your meter is correct and the no load voltage output of your inverter is 93 volts when you are unplugged from shore power with fully charged batteries, you need to have the inverter repaired. However, if you are reading that voltage when you are plugged into shore power, the problem is probably in the shore power circuit not being able to provide enough voltage at your consumption rate. But before you condemn your inverter, test the circuit with another meter to verify that yours is correct.
Gerald
